While I understand what you're saying, you're misinterpreting a few things I was trying to say. First off, I was not trying to 2HKO T-Tar with a Goodra. That's not going to happen. If T-Tar were switched in, with the extra EVs in Defense, it can sometimes take two hits from a T-Tar, allowing it to Hit and Rest. Gooey, as Hrothgar is saying, is a Physically Defensive move on a Specially Defensive pokemon, making it a much less viable ability. While it does take up a lot of space for the healing, it can be an incredibly effective staller and deal out strong, though not murderous hits, on many pokemon it does not have an advantage against simply because of its bulk.Umm...don't switch in on anything that has Earthquake? Shadow Tag is 100000000000 times better than Levitate on a Pokemon like Mega Gengar. If used correctly, it gets at least two kills per match unless your opponent is running something like Tyranitar/Chansey/Blissey/Assault Vest Specially Defensive Hippowdon/(you get the point)
Goodra wastes an item slot it could be using for passive recovery in Leftovers, forgoes Gooey, which slows down physical attackers, and wastes two moveslots on Rain Dance+Rest. If you use a strong physical attack on it, it will crumble, and Hydration+Rest cannot fix that.
252+ SpA Goodra Dragon Pulse vs. 0 HP / 0 SpD Tyranitar in RAIN: 144-171 (42.22 - 50.14%) -- 0.39% chance to 2HKO
Hahahahahahahahahahahaha
Mega Mawile is a viable Pokemon in OU. It has 678 Attack if using an Adamant nature, and it can use Swords Dance, which makes its Attack insane. Also Mega Mawile uses Sucker Punch a lot better than Mega Kangaskhan:
+2 252+ Atk Huge Power Mega Mawile Sucker Punch vs. 252 HP / 252+ Def (custom): 340-401 (96.31 - 113.59%) -- 75% chance to OHKO
+2 252+ Atk Parental Bond Mega Kangaskhan Sucker Punch vs. 252 HP / 252+ Def (custom): 289-340 (81.86 - 96.31%) -- guaranteed 2HKO
I also wasn't saying Mega Malwile isn't viable, simply that I haven't seen it.
EDIT: A Gooey Set:
Goodra Leftovers
Gooey
252 HP/ 252 Def/ 4 SpD
- Acid Armor
- Dragon Pulse
- Toxic
- Coverage Move