Mightyena d (Delta) 2.5/5 The only attack that does reasonable
damage is Gang Up, and it's still not all that reasonable from a
competitive standpoint. There is already a ruling that says Gang
Up will only do +10 damage for each Dark/Metal Pokemon (so you
can't do +20 damage for a Dark/Metal Pokemon). Thus, the maximum
damage you can do is most likely 60-70 damage with a full Bench.
The quickest way to get a full bench is to use Holon Mentor
(gives you 3 Basic Pokemon with 100 HP or less), and Beldum's
that lets you pull more Beldums. For now, I can't yet find a
combination that works really well with Mightyena d.
Nevertheless, 2 energy for an average of 60 damage attack isn't
bad. It's just that if you build your deck with it, you have to
dedicate your entire deck to it.