Evil Nail is the evil version of Nail. He became evil by mistaking a piece of chocolate as Kid Buu (Kid Buu was turned into a piece of chocolate by Super Buu on accident). Nail turned evil but his power level became 1,000,000! But he still hated Frieza and betrayed the Grand Elder. But, soon came Babidi who tried to kill him, because he was the one who ate Kid Buu. Babidi was strong, he summoned Yakon, and Pui Pui. They were no match for Evil Nail.
Babidi then fled in terror but he was defeated by Evil Nail's Eye-Beam.
Back to good form
Suddenly, came an M&M that bounced on Evil Nail's head. Evil Nail ate it not knowing it was a candy-Bulma reverting him to "Good" form. Bulma got wished back though.