What if it uses the Aye-aye freakish fingers to shoot out paint? like a paint gun?
Hmm, OR, if an Aipom evo, maybe the tail hand is now a gland sac which, when pressed, leaks out paint. To better mark territories with the paint, its stubby hands crew long fingernails so that it can both grasp its tail to paint with but also learned to press its nail on the gland sac's opening to make a spray effect.