Deciding on a color scheme for your super costume frightens many a would-be designer, but I think Marvel's Captain Ultra has hit upon the right approach here -- use all of them!
Oh sure, your classic heroes all have a three-color approach, like Superman's red, blue, and yellow, or Batman's gray, blue, and black, or Spiderman's black, blue, and red. But they're not ultra! When you're ultra, the world expects a bit more from you. You have to show up and not just match the other heroes, but surpass them. If they have three colors, you wear four. If they have four, you go for five.
So just to be safe, budding super-hero sidekick (dare you go with "Captain Ultri-mate"?), take a page from your mentor's book and go with blue and red and yellow and orange and green and black. Because Superman might have more powers, and Batman more balls, but nobody wears more colors than Captain Ultra!
And as you can see in the bottom illustration there, no matter what, remember -- Jazz Hands! Always, always Jazz Hands.
(Image and character ©1985, Marvel Entertainment Group, Inc.)