I would snap my fingers thus instantly turning him into a deep fried shell-less turtle covered in a rich BBQ sauce for an extra kick. He would also have an apple in his mouth.

I would turn into the Dark Bowser in my signature and my superior darkness powers would overpower and almost annihilate him and he would get sent flying way off the stage to his loss. That or we would be come friends and oh, I don't know, he'd admit defeat and send me back with the power to transform into Dark Bowser or we would like become allies for eternity and totally own Mario instead of me being sent back...far cooler fate(s).

I got a good one, when I enter the arena where bowser is, I use the shadowclone jutsu, then do the Naruto Barrage technique at bowser. K.O.

I would probably give it my all at first using hand to hand combat, being careful to avoid his fire breath. If that didn't work...I'd probably be pretty beat up and frustrated. Being frustrated, my anger would reach its limit. Then I would use the powers of anger and darkness to transform into DarkLouis. My speed and power would increase and I would defeat Bowser with my finishing move, the anger rush

Why go though the fancy plans when this is just as effective:

Defeat Bowser in three easy steps

1. Grab the shotgun that you borrowed from Conkers Bad Fur Day
2. Aim
3. Blow His Head Off

You don't even need to be near him for this one

1. Pull out your phone
2. Call Osama Bin Laden
3. Tel him bowsers location
4. Tell him the big tower next to bowsers location is about to be demolished
5. Give him a Air Bus 720 (aeroplane)
6. Give him another one
7. Watch the place explode

nice huh, it's called super mario 912

chapter 2

i grab my machine gun and then shot him till he's plain dead

I'd get my plastic sword and go, "DIE YOU FAT IDIOT!" But if he doesn't die, I'll just kill myself, so he can shut up.