This article is from the 2006 series of SMBZ and is no longer canon.
The Heroes vs. Mecha Sonic battle is the ninth battle in the series, between Mario, Yoshi, Sonic, Shadow and the opposing Mecha Sonic, fighting over the silver Chaos Emerald and killing each other. It takes place during Episode 7. The battle ends with the timely appearance of Luigi and the stopwatch being broken, leading to an escape of the Minus World and ending the battle.
8-Bit Mario + Cape Feather = 8-Bit Cape Mario