I actually have to say some of the lost planet 3 bosses, they involved learning how to dodge the bosses attacks, sometimes fighting off other Akrids at the same time, spotting their weak point, and being able to exploit that weak point. It got tough. Like the king crab boss, you had to use your rig (a utility mech) to to grab its claws and lift it into the air. Get out of the rig, and shoot its stomachs up, it would then knock your rig over and you had to evade its attacks until you could climb back into your rig, easier said than done.