SuperDNA is a rainbow-colored liquid that is often seen in a vial. If a Malleo drinks it he'd become a Sutalleo, and if a Weegee drinks it he'd become a Suteegee. Plus, it also gives you mutated powers.
Creation of Suteegee and Sutalleo
Suteegee was created when Luigi made a device that would make a Weegee that would destroy all the other Weegees. However, SuperDNA fell into the device, turning the Weegee clone into Suteegee. Sutalleo was created in a similar manner, though it is unknown who did it. He came out as a perfect Malleo clone but Suteegee was there and used the SuperDNA on Malleo, turning him into Sutalleo.