He is without doubt the toughest boss in the game... unless you count Culex, whom I actually think is easier.
When he creates a mirage and it's your turn to attack, the one to which the arrow is NOT pointing is the one you should attack. It's the mirage. Or perhaps the point of attacking the other one was because the arrow was pointing at the mirage and your goal is to not waste attacks on the mirage... I don't remember, just attack the other one. I believe Mallow's Shocker is your best weapon (it's really a Special attack, I called it a weapon... metaphorically). Keep Toadstool around so she can use Comeback on Mario and Mallow.
