Oh dear.
1) Get any Pokemon you want to exploit that knows Mimic.
2) Get a Smeargle that knows any three moves you want to exploit and Rage.
3) Get a Ditto.
4) Enter a Double Battle. Have the Ditto use Transform on an enemy.
5) Have your Pokemon from step 1 use Mimic on the Ditto to obtain Transform.
6) Switch your Ditto for your Smeargle.
7) Have your Pokemon from step 1 use Transform on the Smeargle.
8) Use up all the PP in Rage before the battle ends.
9) Your Pokemon from step 1 will keep the moves from Transform.
I am now the proud owner of a Ninjask that knows Spore, Mean Look, False Swipe, and X-Scissor (overwrote Rage with the last move). It is the ultimate Pokemon-catching tool.