Sargon gets to thinking. Based on what he knows about the exosuits, the Heavies with their shields and dakka are best suited to infantry, since regular guns don't have a chance in hell of penetrating their defenses.
Mids are probably best for anything like the exosuits you're wearing. They've got a gun for dealing damage, the Kinetic Hammer to knock em around, and they're armored yet fast enough to take some punishment but keep moving.
The Lights would be best on full scale mecha, no question. Smaller things could move fast enough to shoot them and punch through their weak armor, but a big mech? Nope. And then just stab it in a few important looking places, and bam, dead mecha!

The pod clunks as it hits something.
"We're here. Now ascending..."
The pod rises up, slowly breaching the surface of the water. It then slowly moves up against a docking area, and a hatch bursts off the side of the pod, allowing the inhabitants to leave.

Just curious, but is it possible for the team to fail a mission?

Not particularly, but it IS possible for most/all of them to die.

I was just wondering what would happen if they failed a mission. Say a escort mission and the person to be escorted is killed, or some such.

I'm not sure. It'd have to be on a case-by-case basis I suppose.