The original 150 were great, 250 would be fine a stretch, but then they started repeating creatures all over again. There's now about six variations of Pikachu, that are all speedy little lightning-vermin.
Then we have the legendaries; there's something ridiculous like twenty of them now. Way too many.
...And the HM moves! Dear God the HM moves...Surf, dive, waterfall, paddle, float, drown, so many fuckin' HM moves I had two separate Pokemon with nothing by HM moves and the other four to actually battle.
Why can't we have some variation in terms of starting Pokemon too? I mean, Grass-Fire-Water is well balanced in terms of that one is always weak against another, but so would, say, Fighting-Darkness-Psychic.