MK's worst stage is FD. Okay.
Diddy's worst stage is RC. Okay. But is it a bad stage? Lol, not really. Sure, against certain match-ups like MK, but that's the same thing with Diddy vs. MK on FD. Diddy's banana game gets a boost on the ship, he has easier mobility than others across the second third of the stage and can space well with fair, and he can set up for easy kills at the top because of the walk-off, leading to a potential banana lock to death, or banana trip to dsmash/fsmash for a REALLY early kill. Just because the stage isn't flat, doesn't mean it's bad for him.
Snake's worst stage is RC. Now, I don't use Snake that often, but I realize that disappearing C4s and Claymores aren't fun on certain parts of the stage. But the insanely close blast-zones on the ship and the low-ceiling at the top is pretty good for Snake, I would assume. And his nade game is only harshly killed for a third of the two minute cycle.
Wario doesn't have bad stages.
As I've argued a lot of times, quite a bit of characters don't have bad stages, just stages where they do worse at.
And @Falcon, I lol'd.