CMT for this:
Mew [JPN] *NICKNAMEABLE!*
31\31\31\31\31\31 Timid\Jolly\Modest\Careful\Impish\Naive\Hasty\Calm \Bold
I've gotten every single nature except Adamant. It just never appears.
Comes UT at L5. Despite being an event Pokémon, I can nickname it because I RNG'd a game save with the same...