People who insult you after a close match. Hell the other day I was playing against this Mario (well EVERYONE is freakin' Mario now-a-days...) but I beat him game one, pretty close. Game two comes around, and we're both at high percentages, and he manages to take my stock. Good for him, he played well. In the lobby, or whatever you like to call it he changes his name to "U_SUCK" and he goes about name calling and all this other crap, and then leaves. Just irritates me that people feel the need to be insulting to one another for no reason.
Another thing that just ticks me off is people who use almost every top tier character.
Game 1 - Pikachu
Game 2 - Shiek
Game 3 - Luigi
Game 4 - Villager
etc.
It's not fighting against the characters that's the problem, it's that they aren't even good with them, they're just playing them BECAUSE they are top tier. If you like a top tier character, awesome, but if you're just playing him/her because they're top tier, you have some problems.
And lastly, I hate losing dittos because I'm a salty ************
