then which marvel characters would be a good match up for him.
You'd have to enumerate Mario's feats, first.
Able to lift a castle and throw it into space - class 100 strength.
Able to run, fly, and swim faster than a bullet - quicksilver level speed, minimum.
Able to tank lightning bolts, meteor strikes, the heat of stars - Colossus level durability.
Able to hurl fireballs - Human Torch/Pyro energy manipulation.
Transform into Metal Mario - radical durability increase from what he was able to take before.
Throw deadly-pills at people - What the hell would we classify this as?
Able to shake the earth with a divebomb from the sky, without taking any damage himself.
Bust planets in Mario: Galaxy(Apparenty? I haven't actually played. Just echoing this because other people claimed it.)
Seems he'd rank at the upper echelon of mid-tier people, but would still be below the likes of top tiers - the Surfer, Superman, Thor, et cetera.