Nice one there...even tho I knew it was fake..... anyway lets get into trying to use the fiction at hand.
You have a plumper lost in a land of fantasy , so lets do a Alice in wonder land type of plot only change it up into a buddy flick.
First off the hardest thing to deal with is the magical/fantasy elements and adapt them to the big screen. I would go with a green powered based armor and powers a normal power up gives you strength and speed(IE turns a normal guy into an athlete).Nano based armor that installs itself on the skin via gloves and is powered by mushrooms and other Mushroom kingdom plants and icons, different power ups gain you different abilities. Fire flower gives you speed some strength but lets you control fire, hammer suit gives you a vary slow but tough armor that can create a near infinite amount of heavy hammers that you can easily throw.
Goombas are semi sentient organic scouts for the Koopas who are a race of mutated half human half turtle/reptile take a couple races from starwars and merge them toss in a bunch of weed jokes and there you go.