(All of these would be mostly barefeet tickles)
Velma Dinkley (Scooby Doo) That brainy little know it all needs to have a good hysterical laugh. Maybe that is what is needed to take care of that, "lousy meddling kid".
Josie (from Josie and the Pussycats. She's too much of "the girl next store", and acts too prim and proper. Would love to see her in a hysterical fit)
Valarie (also from Josie and the Pussycats. For the same reason I would like to see Velma tickled).
Irma (from Teenage Mutant Ninja Turtles. If April had to face the feather of Don Tortelli, then Irma should to. Maybe its what she needs to finally loosen up)
Brenda, D.D., and Taffy (Captain Caveman's Teenangels).
Jasmine (from Aladdan). She never smiles or laughs!! She's overdue for a good long tickle.
Storm (X-Men). It would be just the thing to take care of that pompous self righteousness of hers.
Rouge (X-men). Obviously, I would have to either wear gloves, or use a feather or other instrument on her soles. She has that southen belle cockiness, and would be the type who would laugh like a mule if she had her soles tickled (She would probably enjoy it too, since she rarely, if ever, gets an effectionate touch from a man).