Magcargo UF is both Fire and Fighting (if Fighting Energy is attached).
Steelix EX is weak to both Fighting and Fire.
Doesn't the damage double, then double again?
So Magcargo with a DRE on it ([2R] Extra Flame (40+) If the Defending Pokemon is Pokemon-ex, this attack does 40 damage plus 30 more damage. ) would do 60 damage, double for Fire weakness to 120, then double against for Fighting weakness to 240. Right?
How about combining that with Grumpig DX ([2P] Extra Ball (50+) If the Defending Pokemon is Pokemon-ex, this attack does 50 damage plus 30 more damage. ) to 1-hit KO the Lugia?
Tech in a 2-2 Lanturn line to 1-shot KO the Blasty if it comes up, and you've got a nasty little 4 corners going.
Throw in some EXP All to keep the energy flowing and I like your chances.