Yeah I find Sableye and Marowak very suspect. The others I wouldn't consider obvious but none of them are grossly overpowered, stat-wise, in their current states, so...
Oh man. I'm here for all of those mega evo's except Kingdra and Ferrothorn. Only because Kingdra I'd expect to get a big sp attack boost when it's already OP in the rain and Ferrothorn is already one of the best mixed walls in the game.
Mega Arceus
All base stats are reduced to 1
All moves are deleted temporarily except for one move
Knows Thousand Arms
Accuracy: 100
Damage: none
Priority: has 40% chance to KO, 40% chance to reduce the opponent's HP to 1, 20% chance to restore the opponent's HP and it status