Most of Gen V, to be honest. Because of college busywork and whatnot these past few years, I haven't really become too invested in this generation, so I haven't spent as much time reading or thinking about these Pokemon. By comparison, I've read through the bulbapedia articles of almost every Pokemon Gen IV and earlier since, back in my high school years, I spent hours just drifting through that site, along with Smogon. Thus, I'm generally much more opinionated toward those Pokemon.
...On a completely unrelated note, TC, I'd still like an apology for the one time you wrongfully criticized Assassin's Creed while knowing nothing about it. :/
XBL: heaven eater; Wii U: AntinomyTG "Pessimism is just an ugly word for pattern recognition." -Anonymous
Plenty Almost all of gen I and II by now The older pokemon get, the more I just accept them, with only the ones I strongly like or dislike standing out
Also most of Gen V. I only did one playthrough of White and White 2, because those games really weren't for me, so there are dozens of Pokémon I've never used that haven't left much of an impression on me.