Board Thread:Speculation, Theories, and Rumors/@comment-25912037-20141223043619/@comment-26808654-20150201013626

WanderIsAwesome2001 wrote: I think Knuckles is the most powerful Sonic character because in Sonic the Hedgehog 3 & Knuckles, he knocked the Chaos Emeralds out of Sonic while he was in his Super Sonic form.

Knuckles has Master Emerald powers, which cancle out the effects of the Chaos Emeralds, which give Super Sonic his powers. Knuckles is a powerful character, but I don't think that counts as him being strong than Super Sonic.