Dr. Eggman (1) - Sonicboom7.
Bowser, Metal Sonic, Dr. Eggman (2, understudy), Srctach, & Grounder - skull902.
"Overworld Rumble: Sonic & Mario" by DJ Pickle (pickleman77) http://www.newgrounds.com/audio/listen/93655
Dr. Eggman made by Silverbolt.
Metal Sonic made by Domenico.
Bowser and ShyGuys made by AJ Nitro.
Super Mario World enemies made by jdaster64.
Scratch and Grounder made by Tonberry2k.
Backgrounds by SkyLights.
Death Egg Zone (Sonic the Hedgehog 2).
Secret Base Zone (Sonic Advance).