This glitch could take you by surprise, because it is (to me) easy to find. You need to Spike Ball ability to do this glitch.
First, you have to go to a certain area of Dimble Woods.
(Made by me)
This area is at the top left corner area of Dimble Woods.
Once you are there, use Bowser's Spike Ball ability and roll onto the wall. You want to get onto this area of the wall.
(Also made by me)
Now, roll up toward the brown part of the wall, which you shouldn't be able to roll on. The arrow just directs you where exactly you have to go. Of course you know this is a glitch so when you do this, your shell does latch onto the wall and you can get out of your Spike Ball Shape by pressing X. However, you don't fall to the ground but instead, you stay standing in midair!
You can move slightly to the right, but if you go to far, you'll far back to the ground. When doing the body slam, Bowser will just be jumping a little but can't body slam at all.
Just maneuver yourself away from the wall or to the left or right to fall off of it.