What about Gm's who power play their character(s)? Once in a naruto rp i had a guy who had a rinnegan (see naruto rp for details beware of spoilers) kid at six to eight years of age or so with stupid amounts of abilities attached to his eyes that weren't even canon with the actual thing. For example he stopped one of my characters from using a SOUND based jutsu that fucks up your brains ability to process stuff essentially rending them to their hands and feet, as well as blocking and sending back a hail of ninja stars my character threw immediately afterward. This was a character whom had been build with high regards in terms of talent. He was for all means and purposes a prodigal son in terms of it. But somehow he gets wrecked after those two attacks happening because somehow he negated both the sound jutsu and sent some sort of telekinetic blast at my character. In reality the kid would have needed to cover his ears or suffer from the attack (which has two post turns of charging) and get stabbed by the ninja stars or take the jutsu and block the physical attacks. You can't stop a ability that travels through sound.

I do my best to keep my characters when I gm to a above average to less extents. In a current naruto rp I'm playing my guy excels heavily in ninjutsu (the physical types of abilities) but sucks in genjutsu (illusions) and has average taijutsu (normal hand to hand combat sort of stuff). The only time I go out of my way to make a powerful character is if the rp needs a base to hold up on in case no one else specializes in that one area or can't be trusted to do so without power playing or the meta game. In exchange for that I make them the jock archetype character who prefers to smash thins as opposed to thinking things through.