Arena should have been increasingly demanding fights that each require a unique build to conquer. Or even better, each fight should have made you use a pre-set loadout, so you’d have to explore and learn new builds, and that knowledge could then be carried into designing mechs for the campaign missions.
I bet theres a lot of people out there not changing it up at all, missing out on an a lot that the game has to offer.
Ideally each one could have made you adapt to and learn new mechanics.
But it seems each one is just a randomized loadout or a character from the story, with the exact same AI slapped on.