You don't know Metal Gear Solid 4

Foxhound… use nanobots
Meryl's elite soldier unit Rat Patrol Team 01 (FOXHOUND), use nano technology to co-ordinate/react wordlessly mid-battle.

Vamp… is immortal, but not scar proof
Vamp's killed - three times - in MSG2, including a head shot (hence the scar), but refuses to die. In MGS4, he's in the chopper with Naomi, so we guess he's working for Liquid, still fighting The Patriots. The secret of his revival? Every time he "dies" in MGS2, he's touched by water…