Fart in a Balloon

The green balloon takes you further off the ground than the other double jump balloons, and it is the only one where the extra height creates a problem. A full jump from flat ground drops you far enough to take fall damage coming back down. Pair it with a Lucky Horseshoe or something else that cancels the landing, or you will be chipping your own health away every time you use it.

The jump pushes you forward as well as up. Turn around in midair and fire it and you reverse direction while keeping most of your speed, which dodges a charging boss far better than raw height does. You can also cut the ascent short by releasing the jump key, which keeps you out of the ceiling in a tunnel.

Different kinds of double jump stack with each other. Two of the same kind do not. Carrying this alongside a cloud item gives you two separate jumps in the air. Carrying two items that both grant this jump gives you one, and wastes a slot.