yes and no... (i think)
you play with 1 character at a time. at the end of it you get Mario, Luigi, Peach and Bowser.
you get "Pixels" which are helpers. Crudge is a hammer, you hit people with. Slim is a pixel that makes you thin and cant get hit with anything and hides you. Thoreau is a hand that you throw and grab and hit objects (enemies too).
basically you can use 1 at a time.
this is not a turn based game like the others. it's more like the original 3 Super Mario Bros. you jump on things, you use items to restore health, hit bricks, ect.
i hope this helps...