Farfetch'd (seems to be one of the only grumpy ones)
Alakazam (according to Wikipedia, it has an IQ of 5000)
Noctowl (hey it's an owl, owls are symbols of age & wisdom)
"Alakazam", "Noctowl" and "Farfetch'd" seem like the best candidates when looking at their appearance.
P.S. Man that took a while, did you people know that according to Wikipedia there are a mind boggling amount of 493 Pokémon!?