I...I guess you can really not have a main. I guess your best character could be considered your main though.
That's what I mean when I say 'main.' I use a bunch of characters, and random, a lot.
Also, this stage looks pretty cool! It doesn't look THAT insane, as these 'mini-games' seem to only last 3 to 5 seconds, similar to Mr. Game and Watch's stage with the wrenches and oil. I wonder what the prizes are? Items or something, most likely.