Typhlosion's not that bad. It's got the same exact stats as charizard (unless the two pokedexes I looked at are both lying)...which is odd, because I never see anybody say charizard is weak or anything. :P In terms of type, maybe, but never in stats.
...Sorry, I just had to say something in defense of one of my favorite pokemon. XD
Anyways...I don't really hate any pokemon, but there are some that I don't like nearly as much as others...namely:
The zubat line - well, zubat and golbat, really...especially golbat, since I don't like its look...but they're annoying little things (and I think almost everyone will agree with me on this). I find zubat to be a bit cute, though, even with its lack of eyes.
Diglett/Dugtrio - especially the ones in the new games that have that stupid Arena Trap ability. :| I hate having to fight these things!
Mewtwo - I find it to be really bland, boring, and overdone...and it being a psychic type doesn't help it for me, as that's one of my least favorite pokemon types.
There's more that I'm not too fond of, but those are the ones I tend to dislike the most...