I don't really get the Gyarados thing either. Maybe it's because it gets so big, or because it's such a dramatic change... But mine still acts pretty much the same. Sometimes he breaks stuff when he's excited, but I don't think he does it on purpose.

[Pesci is... jumpy sometimes.]

I dunno about the Pokédex! I haven't met that many Pokémon yet. [A pause, and he tilts his head with a bit of a pout.] ... I wouldn't mind if it was wrong about Parasect, though.