FitRob07_PM was built specifically to replace the Mario Kart alt version. Remove the _PM from FitRob and FitRob07 and replace in the projectm/pf/fighter/robot folder.  Other outfits will not work on Rob07 unless you add the 6 extra kart bones (Mufflers and wheels) respectively. Look at the bones of the Rob07 or replace the textures if you really want other colours.

Rob07 will work on other slots. Although the extra bones could mess with wifi synch (if you still use the fan wifi servers).

The FitRob pac will remove the Mario Kart smoke trail effect. If you don't want this removed don't use this.