I usually use the B Dasher but I don't really use a specific combination. I beat MK 7 2 times and have to beat it again once more... but I usually role with da boy Yosh if that helps

when i want to use a combo that's fast, i use metal mario, b dasher and monster wheels, but if want high acceliration, i would use toad, egg and roller (you can choose a different character for any as long as it has the same weight class)