The biggest game breaker in Brawl is definitely Meta Knight, who is usually either outright banned or handicapped in competitive play to compensate for the fact that he's so much better than every other character in the game. To wit: he has by far the best recovery in the game (his recovery is so far distanced and has so many options that it's nearly impossible to edgeguard him), transcendent priority and disproportionately far reach in nearly every attack, which makes him difficult to approach, a nearly-unstoppable ledge game (which explains the oft-maligned ledge grab rule), excellent killing and edgeguarding/gimping ability, the ability to glide under the stage repeatedly to stall for time, and a series of particularly devastating moves. In particular, up aerial (being the shortest duration aerial in the game and part of the reason his ledge game is so incredible, as well as being an amazing juggler), down aerial (which gets gimps on characters with poor recoveries, and is incredibly fast), Mach Tornado (which is highly damaging and fast, has an incredibly large hitbox that blocks attacks and covers everywhere but above Meta Knight, and is difficult to punish), Shuttle Loop (which is incredibly fast, has invincibility frames, and its incredibly high base knockback allows it to get very early kills when near the blastline and on lighter opponents), neutral air (highly damaging, incredibly fast, and a reliable finisher), down smash (incredible reach, reliably K Os around 125% with the back slice and 140% with the front slice, and is incredibly fast), and down tilt (which is excellent for attacking shields and has a chance to trip, and it can lock knocked down opponents) are particularly painful to deal with. Also, there is a glitch (which was banned even when the character was allowed in tournaments) to become permanently invincible (and invisible) by utilising a control exploit to extend Dimensional Capes. Meta Knight's only non-negligible weakness is his low weight and poor momentum cancelling causing him to die very early. But with how difficult it is to hit and string successive hits on Meta Knight, and his godlike recovery preventing any early kills from edgeguarding, Meta Knight doesn't have any problems surviving.