How to Beat No. 7 of Mushroom XIII in Kingdom Hearts II

Locating Mushroom No. 7

Go to Twilight Town. Land at Sunset Terrace.

Head down the stairs. Then follow the train tracks until you see the man wearing a green shirt.

Go through the entryway. You'll see a large entryway with "1" written above it - this is the one to go through.

Follow the arrows that point to "2." When you arrive at the entryway no. 2, look left and you'll see the mushroom.

Preparing Your Equipment

Place Thundaga on your shortcut menu. This will be the only attack you need. Since you can't attack the mushroom, spam Thundaga on it!

Place some ethers on your shortcut menu. This is in case you run out of MP before the mushroom dies.

Equip Photon Debugger. This is for added damage to thunder-based magic.

Equip Fatal Crest (Final form). This is for added magic boost. This keyblade is even stronger than Ultima Weapon in terms of magic damage.

Challenging Mushroom no. 7

Drive into Final form. Press ∆ to start the challenge.

Jump and glide away as soon as start. This will keep you from getting hit as soon as the challenge starts.

Circle around the area and spam Thundaga. Be careful when circling around; the area is pretty small, and you might hit a wall and get attacked by the mushroom.

Use aerial recovery if you get hit by the mushroom.

Continue casting Thundaga. The mushroom should die within 5 seconds.