User blog comment:Fedora Lord Para 348/Mewtwo VS Shadow - Explanation Time/@comment-31225410-20160621170744

I just realized Shadow wins if Sonic 06 is used. Solaris is generally accepted as at least Universe level, and potentially much higher. Super Sonic, Super Shadow and Super Silver defeated him. But the thing is, that feat is an outlier. Literally every other feat they have in Super puts them at Planet. And would calling 06 canon really be a great idea, given that it is glitchy, buggy, and generally treated like it doesn't exist by Sonic fans anyway. So should it really be used? The answer here is no. But if Screwattack chooses to use this feat, then the victory goes to edgy Sanic. But otherwise Mootoo has an easy win.

tldr: If an outlier is treated as canon, Shadow wins.