Tails

Who is Tails?
Tails, or Miles Prower is a 8 year old fox. Despite him looking like an innocent friendly fox, he is actually the strongest being in all known, he just doesn't like to use his actual power. He is the strongest, only SCCD is stronger, but it cannot kill him. He can't be defeated, he cannot die. He will always be the strongest, but he will never reveal his true power.

You will never fight him, he never reveals his power, he will never die, and he do anything, you can't hurt him because he reads minds and will erase you out of existence.

Is SCCD stronger?
The answer is: sort of

SCCD is stronger than Tails, but it can't kill him, as Tails is immune to anything, even SCCD itself. But they will never fight, as Tails is just a fox that doesn't reveal his power, and SCCD doesn't even know who he is.