All of this seems fair, so I'll respond to the Kirby vs Mario bit
Mario doesn't do anything particularly extreme to Kirby. He can be combod just fine past a certain percent (when he's in enough hitstun to ignore nair), and Kirby is pretty good at stuffing approaches from Mario. Utilt and bair work great, multijumps help avoid landing on top of Mario, Kirby can trap Mario at ledge reasonably well with just jab thanks to his limited range, Kirby doesn't get combo'd too hard to my knowledge (I remember Dunnobro said otherwise, but IDK anything about that), Kirby's tilts keep Mario out super well, particularly forward tilt (but utilt is amazing for jump ins)... Really, the main issue here is that Mario is way more mobile than Kirby. I like to play the Mario MU (and the Sonic MU, tbh) by constantly walking away from him and punishing his attempts to get in, and mixing up grabs. When he's at the ledge, I keep him there as long as possible. But Mario doesn't really do anything too special to Kirby, IMO.
I know Dark Wizzy gives the MU the same ratio I would - 55:45. The MU isn't too troublesome, IMO.
). Cloud's prevalence as a secondary may not lead him to be what we define as 'solo viable' but with the absolute mish-mash of characters we normally see at top level, perhaps the fact he's seen even as a worthy secondary, the fact that he's still this imperative to players' viability makes me think he might actually be the most consistent, might be the character where practically his flaws don't matter as much as we give them credit for, might be the best overall in the game to help you make it through bracket?
