Obadiah Koopa sports a striking resembalince to Bowser, but with a few differences. He has gray hair instead of orange, due to old age. He also wears a white tuxedo over the front of his shell. Like Bowser, he has sharp teeth (with one gold tooth) and a slightly hunched over position. He also has showing feet and hands, like Bowser.
Unlike many characters in the crossovers, Bowser isn't actually to much different personality-wise than Obadiah. They are both greedy villians that want a Mario family member out of their lives, and they both have fairly clever ways of doing so. But, very unlike Bowser, Obadiah is a technical genius with one well thought out plan that almost succeded. Obadiah could easily figure out that the Iron Mario mk. 2 armor belonged to Tony, and he thought of a good way to distract Tony that almost worked. Obadiah overall is a secretly greedy buisnessman that wants Mario Industries to himself