I like this set. Also Cacnea can learn Nasty Plot via egg move, so I'll also make a set for that, seeing as his attack and special attack are equal. Cacnea cries for a trick room team.
Nasty plot-Makes cacnea a killing machine that still lacks speed.
Energy ball(TM)-STAB power.
Hidden power (Rock)/-If you can get hidden power, it covers 4 of his weaknesses.
Sucker Punch-Though it's physical, priority moves are still good, not to mention the fact that CAcnea still has good attack power.
Other good moves: