I have always had a very hard time picking a #1 favorite Pokémon. There are so many amazing ones, I can never pick just one. So to make this somewhat fair (because I can't do this any other way), I'm going to post my favorite Pokémon from every generation. These are displayed in my signature, but I am not going to do both regular and legendary/mythical or any other sub-categories here in this post, just one Pokémon from each generation.
Kanto:
Abra was always one of my childhood favorites, I thought it was a mysterious and interesting creature. I had also heard that Psychic-types were supposed to be really tough and near-invincible, but I did not get to learn this since I never seriously trained any Psychic-types of my own in Gen 1. I remember that the anime and the scary way they portrayed Sabrina and her team there made me super terrified when I faced her the first time in Blue... but she turned out to be a pushover as my Blastoise OHKO'd her entire team with Hydro Pump! I think I was quite overleveled though.
As for Abra, I trained one in my first playthrough of Blue, but I never evolved it though because I liked it better than its evolutions. I don't think I had the ability to evolve it all the way into Alakazam either since it was a trade evolution and I didn't have the abilty to trade until later. I still used my Abra a lot though, but only in one way. I taught it Metronome and let it battle against wild Magikarp at level 5 just to see which cool moves Metronome would bring up. But why is Alakazam my favorite, and not Abra? Because in Gen 3, I realized that fully evolved Pokémon were the best for battle purposes (with some exceptions). Alakazam has very high Sp.att and Speed which appealed to me, so it became my favorite from Gen 1 and it has been that way ever since.
Johto:
Once when I played Silver as a kid, I spent an entire day training a Ledyba to evolve into Ledian. It started at level 10 and finally evolved at level 18. I think it was also very late at night when it evolved, I was in bed and was supposed to be sleeping, but I just wanted to evolve it before it before the day was over. Nowadays, I would have gotten something like that done in 5 minutes. But back then, it was a big thing for me. Since that moment, I have always had a fondness for Ledian. I think its design is just awesome. I got Silver before Gold and I have always liked Ledian over its Gold counterpart Ariados. As for how Ledian works in battle, I have used it seriously (more or less) twice and it wasn't all that great, which is what should be expected. But I still like it! It has been my favorite from Johto for a long time.
Hoenn:
Before the release of R/S, I had obtained a guidebook (which in retrospect was rather lackluster and limited), but it featured all of the new Hoenn Pokémon at least. One of them was Latias. I thought it looked really cute. My first Hoenn game was Ruby, and I had learned that Latias would be available in it. But in reality, that wasn't the case. Because getting a Latias in Ruby required you to have the Eon Ticket. The regular legend I got was Latios instead. While my friend (who had Sapphire) got Latias in his game. We were both quite surprised, especially since I liked Latias better while he preferred Latios, and their colors did not match the game colors! My friend played through Sapphire but then he wanted to restart his game, though I had asked him to find and catch Latias first and then trade it to me since I needed it for my Pokédex (he did not care much for completing his Pokédex). He eventually found Latias and caught it with the Master Ball, gave it to me, and restarted his game.
I have always liked Latias since the early Gen 3 days. It was my choice for the roamer in Emerald, I have always liked it better than Latios even if I really like Latios too. I even specifically RNGed myself two shiny Timid Latias with perfect IVs, one in HeartGold and one in White 2. However, while I do like regular Latias, I am not a super huge fan of Mega Latias. I don't think it looks too interesting design-wise, and I think it and Mega Latios look way too similar to each other. Regular Latias is my favorite Hoenn Pokémon though.
Sinnoh:
Shaymin became my favorite from Sinnoh after I realized how many positive qualities it had. This was in the very early Gen 4 days, before the English release of D/P. A person I looked up to made a forum post about all the positives of Shaymin (which was known as "Shiemi" at the time) and how it symbolized gratitude, kindness, and other positivies. All of which was embodied in the form of a cute little hedgehog which might not be the strongest Pokémon in battle despite being a mythical, but it has a great signature move that allows it to do something special at least. Ever since then, I have been a huge fan of Shaymin. When I played D/P, I loved the backstory for Floaroma Town and how it was secretly about Shaymin. In Platinum, Shaymin got a new Sky Forme which was much more powerful in battle even if I prefer the design of its Land Forme. Platinum is also where I finally got to catch a Shaymin of my own thanks to the Wi-Fi event giving access to it.
Unova:
I first heard about Haxorus before I started playing B/W. I thought it was crazy, a Pokémon with "hax" in its name. Could that really be true? It was also a powerful mono-Dragon with a cool design. When I played Black, I decided to use an Axew on my in-game team just to see if it was really true that its final evolution was named Haxorus. And it was. I kept Haxorus on my Black team and it really worked well, its massive Attack stat allowed it to destroy most opponents. Mold Breaker was great too. I have since then had great success with it in many other teams, mostly in Gen 5. I think its design is really awesome as well. It is also interesting how Haxorus was apparently the first Gen 5 that was created.
Kalos:
X/Y and Gen 6 introduced the Fairy-type. For the first time since Gen 2, a new type was added to Pokémon. I really wanted to learn how it functioned, so I wrote down its offensive and defensive characteristics on a paper which I had by my side while I played X, which was my first game from Kalos and Gen 6. I also wanted try the Fairy type as soon as possible, so I decided to use a Fairy-type on my in-game team in X. But which one? A new one, of course. Not an old one which had gotten retyped. But which new one? I quickly settled for Sylveon. It was super adorable. I tend to love new eeveelutions, my previous favorite Glaceon would soon find itself replaced.
Back when X/Y were new, it wasn't completely clear how to evolve Eevee into Sylveon. Some things were known, but not all the details. First of all, Eevee needed to know a Fairy-type move. I heard that there was a Fairy-type move that existed as a TM in X/Y, but it was apparently available late, after the 6th Gym. And said TM is Dazzling Gleam, which Eevee can't even learn! Then I learned that if you caught a wild Eevee at level 19 on Route 10, it would know a Fairy-type move upon capture. So I caught one at level 19, and it knew a Fairy-type move in the form of Baby-Doll Eyes. However, that was not all. You also had to do something with it in Pokémon-Amie and the let it gain a level. Only after all of that, you would get a Sylveon. But what exactly did you have to do? According to a Youtube video I watched, you had to max out all three categories in Amie: affection, fullness and enjoyment. So I started doing that, expecting it to take a while. Then I read in the comments of that video that someone had gotten their Eevee to evolve into Sylveon by leveling it up immediately after it had gotten a huge burst of hearts in Pokémon-Amie (gaining a new affection level, but that wasn't know back then). I trained my Eevee so that it was close to gaining a level, then played with it in Amie until it got a burst of hearts, let it gain a level, and... it evolved into Sylveon!
Since then, I kept Sylveon on my team in X, learned everything about the Fairy-type (which also became my new favorite type) and I loved it. Ever since my playthough of X, Sylveon has been my favorite Pokémon from Kalos. I have had great success with it in many other teams too, inlcluding post-game teams, Battle Maison/Tree teams and even one of the very few online teams I have made. I (and the rest of the fandom) also learned about what was actually needed to evolve Eevee into Sylveon eventually.
Alola:
I have a strong dislike for dogs in real life, but I tend to like dog Pokémon. And while I'm not fond of regular dogs, I tend to like other dog-like creatures such as foxes and wolves. The same goes for Pokémon based on these creatures. My first Alola game was Moon. While I completely skipped training a Lycanroc there, it had gotten me interested. When I got Sun, I decided to use a Lycanroc on my team there since it had the Midday form which I liked better than the Midnight form. However, it had a rough start. I remember that it was really weak at first. As a Rockruff, it lost against wild Caterpie before it learned Rock Throw! Then it gradually got stronger, and it eventually became one of the most important and dependable members of my Sun team. I lated used one on my post-game team in Sun as well. In US/UM, Lycanroc got a completely new form, and I really wanted to train it somewhere. I ended up using a Dusk Form Lycanroc on my mid-game team in Ultra Moon, and it was great. As for the forms, Midday is my favorite, closesly followed by Dusk. Midnight is my least favorite but still okay, though it is the only one I have never used anywhere.
Galar:
The newest generation, and the one I have the hardest time picking a favorite from. But I'm going for Copperajah. It all started in the intro when I started playing Sword. I went into the game 90% unspoiled, so when I saw Rose send out a Cufant, my first thoughts were: "What is that cute little elephant? I want one!". Elephants are another animal I like, and I was glad there was another elephant Pokémon besides the Phanpy line. When I played Sword, it took a while before I got to catch a Cufant of my own. I remember seeing one outside of the second Galar Mine next to a worker, but there were no elephants to be found in the mine. Much later, I managed to find myself a wild Cufant in the wild area and I added it to my team pretty much immediately. It eventually evolved into Copperajah, a really cool elephant. I kept it all the way to the end, it became a member of my Champion Team in Sword. I thought Copperajah was very dependable. A bit slow, but it had great bulk and could hit hard with strong moves. Steel was also a rather useful typing. I have also had great success with it in raids. So it is my favorite from Galar.
I wanted this post to become short, but I had so much to say that it became rather long. Sorry about that. But writing this was pretty fun. Thanks Bayleef030 for making this thread!
Kanto:
Abra was always one of my childhood favorites, I thought it was a mysterious and interesting creature. I had also heard that Psychic-types were supposed to be really tough and near-invincible, but I did not get to learn this since I never seriously trained any Psychic-types of my own in Gen 1. I remember that the anime and the scary way they portrayed Sabrina and her team there made me super terrified when I faced her the first time in Blue... but she turned out to be a pushover as my Blastoise OHKO'd her entire team with Hydro Pump! I think I was quite overleveled though.
As for Abra, I trained one in my first playthrough of Blue, but I never evolved it though because I liked it better than its evolutions. I don't think I had the ability to evolve it all the way into Alakazam either since it was a trade evolution and I didn't have the abilty to trade until later. I still used my Abra a lot though, but only in one way. I taught it Metronome and let it battle against wild Magikarp at level 5 just to see which cool moves Metronome would bring up. But why is Alakazam my favorite, and not Abra? Because in Gen 3, I realized that fully evolved Pokémon were the best for battle purposes (with some exceptions). Alakazam has very high Sp.att and Speed which appealed to me, so it became my favorite from Gen 1 and it has been that way ever since.
Johto:
Once when I played Silver as a kid, I spent an entire day training a Ledyba to evolve into Ledian. It started at level 10 and finally evolved at level 18. I think it was also very late at night when it evolved, I was in bed and was supposed to be sleeping, but I just wanted to evolve it before it before the day was over. Nowadays, I would have gotten something like that done in 5 minutes. But back then, it was a big thing for me. Since that moment, I have always had a fondness for Ledian. I think its design is just awesome. I got Silver before Gold and I have always liked Ledian over its Gold counterpart Ariados. As for how Ledian works in battle, I have used it seriously (more or less) twice and it wasn't all that great, which is what should be expected. But I still like it! It has been my favorite from Johto for a long time.
Hoenn:
Before the release of R/S, I had obtained a guidebook (which in retrospect was rather lackluster and limited), but it featured all of the new Hoenn Pokémon at least. One of them was Latias. I thought it looked really cute. My first Hoenn game was Ruby, and I had learned that Latias would be available in it. But in reality, that wasn't the case. Because getting a Latias in Ruby required you to have the Eon Ticket. The regular legend I got was Latios instead. While my friend (who had Sapphire) got Latias in his game. We were both quite surprised, especially since I liked Latias better while he preferred Latios, and their colors did not match the game colors! My friend played through Sapphire but then he wanted to restart his game, though I had asked him to find and catch Latias first and then trade it to me since I needed it for my Pokédex (he did not care much for completing his Pokédex). He eventually found Latias and caught it with the Master Ball, gave it to me, and restarted his game.
I have always liked Latias since the early Gen 3 days. It was my choice for the roamer in Emerald, I have always liked it better than Latios even if I really like Latios too. I even specifically RNGed myself two shiny Timid Latias with perfect IVs, one in HeartGold and one in White 2. However, while I do like regular Latias, I am not a super huge fan of Mega Latias. I don't think it looks too interesting design-wise, and I think it and Mega Latios look way too similar to each other. Regular Latias is my favorite Hoenn Pokémon though.
Sinnoh:
Shaymin became my favorite from Sinnoh after I realized how many positive qualities it had. This was in the very early Gen 4 days, before the English release of D/P. A person I looked up to made a forum post about all the positives of Shaymin (which was known as "Shiemi" at the time) and how it symbolized gratitude, kindness, and other positivies. All of which was embodied in the form of a cute little hedgehog which might not be the strongest Pokémon in battle despite being a mythical, but it has a great signature move that allows it to do something special at least. Ever since then, I have been a huge fan of Shaymin. When I played D/P, I loved the backstory for Floaroma Town and how it was secretly about Shaymin. In Platinum, Shaymin got a new Sky Forme which was much more powerful in battle even if I prefer the design of its Land Forme. Platinum is also where I finally got to catch a Shaymin of my own thanks to the Wi-Fi event giving access to it.
Unova:
I first heard about Haxorus before I started playing B/W. I thought it was crazy, a Pokémon with "hax" in its name. Could that really be true? It was also a powerful mono-Dragon with a cool design. When I played Black, I decided to use an Axew on my in-game team just to see if it was really true that its final evolution was named Haxorus. And it was. I kept Haxorus on my Black team and it really worked well, its massive Attack stat allowed it to destroy most opponents. Mold Breaker was great too. I have since then had great success with it in many other teams, mostly in Gen 5. I think its design is really awesome as well. It is also interesting how Haxorus was apparently the first Gen 5 that was created.
Kalos:
X/Y and Gen 6 introduced the Fairy-type. For the first time since Gen 2, a new type was added to Pokémon. I really wanted to learn how it functioned, so I wrote down its offensive and defensive characteristics on a paper which I had by my side while I played X, which was my first game from Kalos and Gen 6. I also wanted try the Fairy type as soon as possible, so I decided to use a Fairy-type on my in-game team in X. But which one? A new one, of course. Not an old one which had gotten retyped. But which new one? I quickly settled for Sylveon. It was super adorable. I tend to love new eeveelutions, my previous favorite Glaceon would soon find itself replaced.
Back when X/Y were new, it wasn't completely clear how to evolve Eevee into Sylveon. Some things were known, but not all the details. First of all, Eevee needed to know a Fairy-type move. I heard that there was a Fairy-type move that existed as a TM in X/Y, but it was apparently available late, after the 6th Gym. And said TM is Dazzling Gleam, which Eevee can't even learn! Then I learned that if you caught a wild Eevee at level 19 on Route 10, it would know a Fairy-type move upon capture. So I caught one at level 19, and it knew a Fairy-type move in the form of Baby-Doll Eyes. However, that was not all. You also had to do something with it in Pokémon-Amie and the let it gain a level. Only after all of that, you would get a Sylveon. But what exactly did you have to do? According to a Youtube video I watched, you had to max out all three categories in Amie: affection, fullness and enjoyment. So I started doing that, expecting it to take a while. Then I read in the comments of that video that someone had gotten their Eevee to evolve into Sylveon by leveling it up immediately after it had gotten a huge burst of hearts in Pokémon-Amie (gaining a new affection level, but that wasn't know back then). I trained my Eevee so that it was close to gaining a level, then played with it in Amie until it got a burst of hearts, let it gain a level, and... it evolved into Sylveon!
Since then, I kept Sylveon on my team in X, learned everything about the Fairy-type (which also became my new favorite type) and I loved it. Ever since my playthough of X, Sylveon has been my favorite Pokémon from Kalos. I have had great success with it in many other teams too, inlcluding post-game teams, Battle Maison/Tree teams and even one of the very few online teams I have made. I (and the rest of the fandom) also learned about what was actually needed to evolve Eevee into Sylveon eventually.
Alola:
I have a strong dislike for dogs in real life, but I tend to like dog Pokémon. And while I'm not fond of regular dogs, I tend to like other dog-like creatures such as foxes and wolves. The same goes for Pokémon based on these creatures. My first Alola game was Moon. While I completely skipped training a Lycanroc there, it had gotten me interested. When I got Sun, I decided to use a Lycanroc on my team there since it had the Midday form which I liked better than the Midnight form. However, it had a rough start. I remember that it was really weak at first. As a Rockruff, it lost against wild Caterpie before it learned Rock Throw! Then it gradually got stronger, and it eventually became one of the most important and dependable members of my Sun team. I lated used one on my post-game team in Sun as well. In US/UM, Lycanroc got a completely new form, and I really wanted to train it somewhere. I ended up using a Dusk Form Lycanroc on my mid-game team in Ultra Moon, and it was great. As for the forms, Midday is my favorite, closesly followed by Dusk. Midnight is my least favorite but still okay, though it is the only one I have never used anywhere.
Galar:
The newest generation, and the one I have the hardest time picking a favorite from. But I'm going for Copperajah. It all started in the intro when I started playing Sword. I went into the game 90% unspoiled, so when I saw Rose send out a Cufant, my first thoughts were: "What is that cute little elephant? I want one!". Elephants are another animal I like, and I was glad there was another elephant Pokémon besides the Phanpy line. When I played Sword, it took a while before I got to catch a Cufant of my own. I remember seeing one outside of the second Galar Mine next to a worker, but there were no elephants to be found in the mine. Much later, I managed to find myself a wild Cufant in the wild area and I added it to my team pretty much immediately. It eventually evolved into Copperajah, a really cool elephant. I kept it all the way to the end, it became a member of my Champion Team in Sword. I thought Copperajah was very dependable. A bit slow, but it had great bulk and could hit hard with strong moves. Steel was also a rather useful typing. I have also had great success with it in raids. So it is my favorite from Galar.
I wanted this post to become short, but I had so much to say that it became rather long. Sorry about that. But writing this was pretty fun. Thanks Bayleef030 for making this thread!