I don't see any good reasons to use any Mismagius set in 6v6 battles. You can probably get it to work if you're skilled enough (or if your opponents are extremely nooby), but there are better ways if your goal is to win as often as possible. These are the two options you should be trying instead.
Gengar: Upon mega evolving, Gengar gains shadow tag. This makes Gengar an extremely reliable revenge-killer, as you can use it to selectively target opponents and, once on the battlefield, the opponent can't escape. Its amazing stats and movepool that includes sludge wave, taunt, and destiny bond gives it a wide range of threats that it can trap and eliminate.
Blacephalon: Blacephalon's STAB attacks will cover just about everything. Because of its stats, it can outspeed and one-shot many common Pokemon, which lets it sweep or force switches. If used with a choice item (which you should use it with), then you can trick your choice item onto any particularly annoying walls that the opponent has.
