In my recent chat with Ryota Niitsuma, the producer behind Tatsunoko Vs Capcom, I was shocked by how sincerely and repeatedly the guy spoke well of Nintendo, and how interested he was in borrowing from them. When I asked what kind of games he'd like to put on the Wii, he told me point blank that he'd like to make "Smash Bros-type game".
If you've played Tatsunoko vs. Capcom, you already know how closely the game controls to Smash Bros when using the Wii remote-alone control scheme. As much as old-schoolfighting games may hate to admit it, Smash Bros is the most popular 2D fighting game on the planet right now, and part of that comes from the fact that anybody can pick up the game and start pulling off crazy sh*t right off the bat.
It's not just the accessibility that Niitsuma-san is looking to borrow from Nintendo, but their characters as well. I asked him if, hypothetically, he could take a character from any other game developer and use them in his next Vs game, who would he choose, he pointed at a picture of Mario and said "Something along the lines of that." It was funny how he wouldn't say Mario's name out loud, almost like he didn't want to take the Lord's name in vain.
Niitsuma-san has previously reported that Wrecking Crew, one of Mario's first games, was one of his favorites growing up. Seeing as Tatsunoko vs. Capcom is a big nostalgia trip for the producer, I could see how he'd also want Mario in his next fighting game along with his other childhood heroes. I'm sure that the fact that every Mario sells in the millions doesn't hurt either.