If you could get a decal made of either their logo or their photo, the younger girls really like the picture cakes. for extra decorations around the sides or as a border at the bottom you could use fondant music notes and/or microphone with a long cord that wraps around the bottom of the cake.
Also adding cheetah spots would work.
Good luck.
D
I found this link on the internet http://heavenlydelightcakes.com/gallery/Children/11%2010%2006%20Cheetah%20Girls.JPG I hope it gives you some ideas.
There are tons of them in the galleries:
http://www.cakecentral.com/modules.php?name=gallery&meta=search&type=full&search=cheetah+girls
I especially like this one inspired by their new movie:
http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=1257735
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