I found it to be extremely easy. Who knew that he was weak against physical attacks? All I did was have a bunch of attack cards, a Larxene card, a Vexen card, a Wight Knight card, a few Hi-Potions, and some Cures just in case.

At first, I used sleights to destroy the two scythes on the nobody. Then, I waited for him to use a card, and I used my Hi-Potion card to reload all my attack cards that I lost using sleights. After that, I activated the Float ability using the Wight Knight card. I just had to jump up and use three attack card (not in a sleight) to attack him until the three reloads were done.

Afterward, I used the Larxene card to get faster. You know when he dashes at you, and if you break him, you can get on board? Well, I got on board, got rid of the shooting pistils, and I ran up to him with the speed of Larxene's Dash ability to slash him with him being able to attack back.

Now, I used Vexen's card just to prevent dying. I broke his card, and when the cursor locked onto him, I attacked him with three attack cards. I just kept this up until he died, making sure to use Curaga every time I got low on health.