I basically started out with my Chandelure and Flygon. Chandelure spammed Minimize, while i used Flygon to do some damage with Dig (i don't have earthquake on him xD)
Then, when Chandy had 6 stacks of Minimize and Flygon had fallen, i just used Chandy to spam Shadow Ball, Flame Burst and Confuse Ray to kill the opposition while the other mons healed Chandy for any hits that came through.
The field actually worked in my favor, as it activated Chandy's Flashfire so that my Flame Burst actually did some damage when Shadow Ball ran out of PP.
Quite an easy battle, though the RNG got me a few times before I won...