Another useful tactic is to duck for cover and toss a Grenade at them. The Robot Guards are red chunks of metal that have the ability to hover. In addition to defying gravity, they also can serve up a damaging dose of firepower. Toss a Pulse Zap their way and sit back and watch them sizzle. Continue pressing the Kick Button to stomp them all to death.
Troopers are bigger, badder, versions of Shooters.
Not only are they a lot more buff, but they care some pretty big weapons. When encountering a Green or Blue Trooper, or even two or more Red Troopers, it is useful to use the Turbo ability and take each of them down with a single punch or kick. If there was ever an enemy who looked a lot tougher that he really is, it is the Android. You'll encounter plenty of these human-looking robots in the Protox Research Lab. Beware the gunplay and deal with them with either a single Laser Pistol Blast or a couple of kicks and punches.