i can only come up with the moveset that is in the generation 3, so here it is
-toxic (well, isnt it obvious?)
-return (if ur Pokemon loves you alot,STAB)/double edge(if ur Pokemon dont really love you,STAB)
-shadow ball (this move would make a ghost type Pokemon literally cry,because ghost move cant touch wigglytuff, and ghost moves are effective on ghost type Pokemon.
-psychic (you do want to fight off fight type Pokemon,dont you?)