Corrected entry: Throughout the film, it is emphasized that Pokémon are behaving strangely because they've noticed the changes in nature. This same rule should apply to Meowth (who is still a Pokémon regardless of his human-like behavior), yet he never seems affected.
Phixius
18th Sep 2013
Correction: This particular Meowth is not a normal (no pun intended) Pokémon. He does not behave naturally, and therefore the shifts in nature do not affect him in the same way. Other Pokémon are wild animals or tamed pets, while this Meowth is a fully cognizant intelligent being. Perhaps he feels it, but he is at the very least able to resist responding to it.
Phixius ★