Mega Man Powered Up/CWU-01P

Boss: CWU-01P
Stun weapons: Thunder Beam

This is the second boss of the Wily stages, and is also one of the hardest to defeat. Not only is the battle underwater, but there is a vortex (current) that will force you to the center of the stage if you stay still, and the boss is protected by a large bubble. There are also two Guts Blocks at the start.

On Easy CWU will move in a square pattern and shoot a green bullet at you. On other difficulties he'll use his laser attack that drops two Guts Blocks from the ceiling and sweep across the room. CWU-01P has 5 phases where the color of his eye changes (at the start it's blue, then it becomes green, yellow, orange and red). In the last 2 phases he also moves very fast, but you can use Time Slow to slow him down for a while if you play as Mega Man or Time Man.

CWU's weakness is Super Arm. Oil Slider is a secondary weakness. Oil blob deals 4 damage and the oil sled deals a whopping 10 damage. Thus you'll take out his bubble shield in 5 hits with blobs and in 2 hits with the sled.