The Adventures of Sonic the Hedgehog

Coconuts knocks a bunch of chemical mixes off a shelf into a vat. Robotnik falls into them and gains super powers as he challenges Sonic to a series of physical tests - and the one who loses the most has to leave Mobius forever! Robotnik's only weak point is his butt, since it was the only part that didn't touch the chemical. Sonic puts a pin on his chair, and Robotnik loses his powers. And though he loses, Robotnik doesn't leave. Scratch, Grounder, and Robontik quote: ""And you two! I'm demoting you two to floor cleaners!"" ""But why? We didn't even do anything!"" ""Exactly!""