Looking for some extra creative help!

I will be making a cake for a graduation party for 3 girls. Two of the girls call themselves Batman and Robin and the third girl is their Superstar Sidekick! Their school colors are red, black, and white. They wanted something stylish but that incorporated their nicknames and school colors. I thought about doing a tiered cake for them comic book style, a la the movie Sin City. But then I thought to myself, that's not really girly or super stylish. So now I'm at a loss.

Any ideas from my caker friends out there? Any suggestions would be helpful!

Oh and I don't want it to look like a 5 year old boys birthday cake!

PLEASE HELP!!!!

Talk with the girls and see what they think? When they came to meet with you were they dressed up super feminine? I'd think that would be a super cool cake to have, but that's just me