Overkills for all the stages in this game. There are certain conditions that need to be met to use them but I won't go into detail about that here. Gamefaqs has an Overkill FAQ you can use if you want to know more.
From Wikipedia:
Eternal Champions is a 2D fighting game originally conceived by Scott Berfield, produced by Mike Latham for Sega of America and was developed by the Sega Interactive Development Division.
Learn about Eternal Champions
