Awesome start for the guide!
I am still new to battle tree compared to all you veterans and have limited knowledge and can't recall different sets of pokemon on top of my head, but what I think this can really help people like me a lot in all those trial and errors, is if there is one end to end example of picking a core, flow of battle, pros and cons and some rating, that would be very useful!!
Things that only experienced players would have, such as mentioning specific surprises that anyone could make that your team will face that might cost you a game (e.g. ice punch electivire if you are running garchomp in your team) that might not all make into a typical threat list. As most of my loses now are due to surprises of moves like this that just utterly destroyed the momentum and type weakness synergy to handle the rest of the fight.
Another possible section that I think would help a lot of newbies is the tactics to salvage if you lose one of your important mons using advanced tactics like switch stalling while keeping an eye on the AI mon's switching pattern and pp to a specific point, all while using the example team.
I can give an example right now:
Team i'm going to use:
1. Garchomp with LO, Jolly nature, EV 252 att / 255 spe / 4 SpD, Sub / SD / Outrage / Earthquake
2. Tapu fini with Choice Specs, Modest nature, EV 252 HP / 252 SpA, Moonblast / Confide / Scald / Grass knot
3. Mega Scizor with Scizorite, Adamant nature, EV 252 HP / 252 SpD, SD / Roost / Brutal Swing / Bullet Punch
General flow of the battle (first time writing this, so I'm trying to be specific, but a lot of general and common flows/patterns can be extracted from a lot of successful cores in the leaderboard team)
1. If Garchomp is on the field as lead, EQ if the move is super effective and you are faster than the Mon using the damage calculator, SD if EQ is not super effective, the opposite mon has no means to 1-2 HKO you and will not use status (look through the moveset spreadsheet at all possible set, look for typing weakness specifically), Sub if it has status and you are faster, Switch if none of the above are true
2. Switch to Tapu fini to prevent any status for 5 turns, remember to keep track of your remaining misty terrain so you can safe switch in with either your alive Garchomp or Mega Scizor, status move or move with side effects are very common strategy used by battle tree teams, a lot pre-20 battles, and still happens post-20. If you have to make decision to keep tapu fini alive and kill your other teammate, keep tapu fini alive always, trust me. Once you are in Tapu fini, attack if your moonblast is neutral or super effective as your choice specs boost your attack a lot and you are very bulky to tank most special attacks and some physical attacks. If you don't take a lot of damange on switch but has no super effective moves, use confide (only if the mon's main attack is special) usually will make your teammate with a lot easier times. Switch, only if you take more than 35% of your health on switch in or have no moves that can do damage.
3. Switch to either garchomp or mega scizor depending on the typing advantage. E.g. ice, rock to scizor and ground, dark, to garchomp, I would highly recommend opening up a tab in the background to check your mon's type weakness at all times.
4. If you switch to mega scizor, most likely it is 1-2 turn left of your misty terrain, make sure you make setup as your first priority so that you can bullet punch after the turn misty terrain is gone to sweep. If not, switch it back to tapu fini if the opposite mon still relies mostly on status moves (any status, such as flinch *yes i'm looking at you fake out*, confuse, sleep, etc all counts).
5. Win as the switching between tapu fini to maintain the misty terrian and remove some nasty mons and the setup and bulkiness of garchomp and mega scizor will win you the game eventually.
General mistakes that will happen using this team and the flow above
1. Switch into a mon and have misty terrain gone on the turn, and get status
2. Switch into a mon and got killed by cover moves (e.g. ice punch electivire that will make you sad when you see your garchomp's health shrink to zero in mere 1 second)
3. OHKO moves (e.g. Dugtrio)
Pros of this team
1. A lot of threats mentioned will be nullified as misty terrain prevent any of those from happening. You can rest assure you will get that victory in pre-20 battles easily usually within 5 turns either garchomp sweep or after switching to tapu fini
2. Battle is a lot easier, as each mon has distinct roles and their defensive typing and offensive typing are usually aligned (so you can usually just look at your move's super effectiveness to determine which mon to switch to)
Cons of this team
1. This is very true especially after 40, where each battle needs to be almost perfect, if you sac/lose any mons too early, you will pay for the consequences (eps. Garchomp, Tapu fini). So I highly recommend you turn on battle animation as that greatly reduce the error you might make when playing hours straight deep into the tree.
2. Still vulnerable to a lot of teams that rely purely on strength. You have no easy way to get out of it (no protect in the team) and if you got unlucky and somehow that fissure dugtrio hit 3 times in a row, your team is doomed.
Some recording of said team in action:
Win: I forgot to record one
I would rate this team as follows
Easy to use and understand: A
This is an A because as mentioned above, each role has distinct purpose, and misty terrain is just too OP for the tree!
Easy to recover from mistakes: B-
As mentioned earlier, as there is almost no overlapping between the mons, if one of your mon dies, the rest of the two will have very hard time recovering the mistake.
Easy to breed: B
1. You can easily get Tapu fini from one of the VGC thread (if you don't mind cloning) in smogon.
2. But the other two you might need some time training, especially Scizor which requires to get an item that is very hard to get and trading with strangers
3. Garchomp is the easiest among the 3 to breed
Complement with how worldie has introduced the tree and explained a lot of AI behaviors, I think this thread that worldie started will be the ultimate guide for battle tree!