LJA4life

Nope, waaaay too early to bring these two in. Imagine a film where you've got 7 koopa kids, Bowser jr as he's probably going to get dropped in as well, then Wario and Waluigi... Too cluttered with 10 antagonists at once and nobody would get enough time to have any back story explained properly/with any depth. Yoshi and the koopalings (you could even hold off on Bowser jr til later if you wanted to) would be more than enough for 1.5-2 hours of entertaining hijinks.

Right after I saw the Mario Bros movie in the cinema with my kids I came up with a theory on how they could potentially get a good 5,6 maybe even 7 movies from this franchise and who would get what.

There's no need to rush this and I said from day one this will be a franchise and a major one that could have a lot of good spinoffs (series and movies) if done right. Melandri and Miyamoto will have looked at the Sonic formula (somewhat ironically) and go down that road if they're smart, which they are.