thanks so much for playing!!
yep, after some feedback, it is definitely unclear how the "choose starting item" room works, so I'll be sure to release an improvement as soon as the voting period is over!
how it works currently is that when you pick one of the three weapons, the most recent one that you picked is equipped. if it is an active item--red madibles or blue-tenna--it is equipped to your Z action slot. green stun is passive, so it is not given a slot. when you find other active items, the button you press--Z or X--determines which action slot it goes into. You can tell it's active by the text at the bottom of the equip screen, which essentially asks "which slot do you want to equip this item?" I'll definitely improve this too
hope this helps you, or others in the future, and thanks for the thoughtful comment! <3