Here is my current lineup. It has been working quite well and rebounded from a lot of deficits simply because of the amount of anti-metal arks near the end of the lineup. Suggestions are of course welcome.
Triphoon
Cyberwurm
Vortexor
Chopperbug
Shadowstalker
Minespider
Chillqueen
Cryowurm
Octoneer
Vegitiger
Golgemios
Scopionix
Magmawurm
Omegawurm
Halopard
I am noticing a lot of earth arks at the end of the lineup as well as metal arks, so the placement of the Vegi, Octa, scorp, and magma are justified for the time being. And the added benefit is that Vortexor can also banish metal arks to the back increasing the likelyhood that they will be scrapped later in the game. But the line-up is pretty solid.
Update: I tried fitting in Ironheart but am out of luck, all it did was weaken the lineup: too many anti-metal arks nowadays. I would like to see a lineup that utilizes this ark to great effect.