I don't mean how well balanced a character is, but how they're designed. The fact that Sonic is good really makes him all the worse because his playstyle often devolves into hit-n-run or just plain runaway, as a character that's super fast with no projectiles. I actually think it's bad for the game for Sonic to be good (Little Mac or Isabelle are other characters I'd say share this trait). But the fact that his moves are so generic just screams for a redesign.
The same is true of Kirby. Almost all of Kirby's normals are generic moves from SSB64, which was also the only game where he was allowed to be good. He's been trash in almost every game since. He's a close range fighter with low mobility, no way to get in, and often pretty poor recovery for someone with multiple jumps. He's pure newb bait thanks to his down-B. Give him more copied abilities from his games and make him more interesting.
Ganondorf also has a lot of bad aspects. He's a clone with a pretty weak moveset. But, he's a very popular character because more likes fair and dair both feel and actually are very strong. There's probably room to change him, especially his uair, usmash, and up+B, without removing the core of his gameplay. He's a character who is bad because his archetype is bad in Smash, but he can be balanced to be a little better without being broken. His issues are in design, not really gameplay (just give him a real recovery).
Hit and run and keep away until the right moment is literally how Sonic fights bosses in his games. It makes sense.