Android Buu is an android built in hell by Dr. Gero and is an modified clone of Super Buu. In hell, the villains got into their own groups and discussed possible revenge plans on the Z-fighters. So Buu multiplied himself, actually dividing himself into two separate entities. Super Buu then took his clone to Dr. Gero, who modified him and based him off of his 15th failed creation, but made sure without that model's problems. He has data on all the z-fighters and knows all their moves.