^It gets me mad when your friends try to ban your character or prevent you from using a certain move. If they say that, you're playing the game well, and that your friends are just bitter over the fact you're more skilled than them.
My brother and his friends always go like "Oh Ness' Back Throw should be banned" because I usually get a KO with that. Well, it's the strongest throw in the game (starts off very weak but the knockback grows by a lot), of course I'll use it LOL
I get mad when I play vs. Mr. Game & Watch because his Smashes are ridiculously strong and have little lag, or Pikachu's Thunder which can stop approaches from the air, and yeah, I get frustrated because of them at times, but I never be bitter and say "oh those moves should be banned".
With items though, it adds luck and easy to grab KOs, so I can understand why people don't like them. To be honest I don't like items either, but I don't mind playing with them on occasion. =P
Then again, there's always item play (like Peach's Turnips, Diddy's Bananas, Snake's Grenades, etc.), so there's still somewhat of a luck factor, but it's still important to learn how to use items like that.
...I kind of rambled on more than I should've, like I usually do about Smash. XP