Does Mario have fire flowers, feathers, stars, racoon suits, hammer brother suits, frog suits, and metal armor stars available to him? If so, there's little Batman can do to stop Mario from jumping on his head 3-6 times and bouncing Bruce off the screen.
Unless, of course, he has "Bat-Italian Plumber Repellent" in his belt next to the can of "Bat-Shark Repellent".
Gender: Unspecified Location: The Museum of Slavic Architecture
The battle would go exactly as follows.
Batman: You're not selling those magic mushrooms on my watch.
Mario: (confused) It's a me Mario.
Batman: Are you threatening me?
Mario (even more confused): Whaa
Batman attempts to go in for a brutal chop but Mario effortlessly dodges and lands on Batman's head.
Batman: Ah my ears, my beautiful ears.
Mario: Whaha
Batman: That's it: Justice League time.
Mario looks up and surprisingly there is a small box above him.
Ten seconds later.
Justice League lie smoking in a crater. Superman's head is squashed.
To add insuklt to injury DC comics is sued by Nintendo of America and lose 500,000,000,000 dollars. Reggie Fils-Aime pronounces himself "satisfied".
__________________ You probably think that just because I'm using the internet at this time that I'm doing nothing. Well the washing up isn't nothing, and I'll be doing that any bloody moment.
Batman is outmatched here in terms of agility and strength. Remember, Mario could swing around Bowser by his tail in Mario 64 (and Bowser was pretty big) plus he could run really fast in Super Mario Bros. 3 and could do backflips effortlessly in Mario 64. Plus he could form fireballs w/o the help of the fire flower in Super Smash Bros.
"Batman would get a mushroom from Mario's homeland, inject it with poison, and throw it at Mario and hope he jumps into it."
Aren't Shrooms already poisonous, well, at least hallucinagenic. Mario's a super powered drug addict and seems to have a high tolerance. He's been on Shrooms and Fireflowers (high grade Chronic) for over a decade. I'm not sure poison would work.
Besides, Batman would have to utilize prep time to pull that off. Mario could get a Game Genie, Game Shark, or Total Action Replay with prep time.
Gender: Unspecified Location: The Museum of Slavic Architecture
Ha people are taking it seriously. Seriously though, Mario cannot lose because he is technically invincible (after all he comes back to life every time he dies)
__________________ You probably think that just because I'm using the internet at this time that I'm doing nothing. Well the washing up isn't nothing, and I'll be doing that any bloody moment.