Board Thread:General Discussion/@comment-27033632-20160215163310/@comment-6858788-20160222001901

Shadow seems to be more powerful than Knuckles is. If Shadow and Knuckles fought in terms of abilities, Shadow would wipe the floor with Knuckles. Shadow seems to have a super form that's still canon, and also the Chaos Powers, like Chaos Spear and Chaos Blast.

Knuckles' strength is quite impressive, but he has a bit of a short temper. Shadow could take advantage of this easily.

Brains over brawn, and Knuckles seems to be more of the latter.