I can't stand Blue (female) in the RBG, and the Y series. She's a complete b*tch in the RBG, and she expects people to do things for her. Also, the reason she gave for stealing Professor Oak's Squirtal was PATHETIC! "I wanted to be a trainer from Pallet Town, too!". God... She flirts way too much. And she dresses like a scank. In the Y Saga, she blamed Lance for her "kidnapping" and almost had Silver kill him.
It also really annoyed me when Red was helping her in the RBG Saga, she was wearing his bloody badges on her ears! What nerve! And she gave Red fake badges. And... Oh, god... I could go on forever. I don't mind her in the GSC, or FR&LG Sagas, but I still can't stand her.
I pretty-much like the rest of the main characters. Red and Green are cool (LATER ON), unlike Blue who never changes. Gold is funny, but a selfish and annoyed moron, Silver is cute, but I don't really like him anymore than Blue, Crystal is stupid and borring, Ruby is funny, but he doesn't know the meaning of "beauty comes from the inside!", Sapphire can be annoying, Wally is cute and nice, but a little whimpy, Emerald is mean and insane, but he's pretty cute.
And, that's it. (I can't stand Misty in the RBG, Y Sagas), ugly and bad tempered. Just like the Anime. At least she changed that in the Manga, though.