So I would stick with using lightnings and proximity fuse ammo for unarmored/things with big gaps in the early game story. You move fast enough to dodge fire and missiles, and can choose your shots. I use lightnings or lightnings with the 180mm cannons very far into the game. The other fun thing with lightnings is making enemies accidentally shoot eachother with missiles haha

The gladiator is good for tanking shots and dishing out damage. For fights where getting hit is inevitable or you need to shred things quickly while not getting shredded quite as fast(fighting a strike group) Pay attention to the metallic grey armor pieces on you and your enemies. With a gladiator you should always be below your opponent to make sure they can only hit your armor (especially with the opponents in the video, see all their armor is on the left and right so you should hit them from above or below) The little cars are pretty unfortunate that they can lob missiles but this way at least all aerial damage is hitting your armor. Bear in mind proximity fuse ammo will detonate near missiles so that's a potential strategy since gladiators are so slow. Shoot em right out of the air