His first form's attack is easy enough to avoid just by luring it in one direction and stepping in the other. As you're moving out of the way, take the chance to jump and hit with the Ice or Elec weapons. You really need to beat the first form without taking a hit. The second form's attack is really hard to dodge, so equip Fire, get in close, and try to nail him with the fire circling Mega Man. You can get in a few shots each time if you're lucky. MM1 Wily was the hardest fight across all six of these ports for me. Just be persistent, you'll get him.