Mega Man X3/Bosses

Dr. Vile
Dr. Vile can only be reached after defeating at least two bosses, and prior to killing Bit and Byte. There are three ways to reach his level:
 * 1) At the start of Volt Catfish's stage, there is a platform that will take you to Dr. Vile.
 * 2) In Blizzard Buffalo's stage, after you enter the small room with two doors, slide down the left side of the first pit you see.
 * 3) In Crush Crawfish's stage, after defeating the mini boss you will see an energy capsule. Walk towards it and you will fall through the floor, discovering a teleportation pad.