
Sometimes you're better off running from these things than you are fighting them (or dropping a Power Bomb on them, which will kill them regardless of color), and thankfully, you only encounter them in the Impact Crater, so they're not too hard to avoid (in Trilogy, Fission Metriods can be encountered in the Phazon Mines, and they're no less annoying). They take a long time to kill, and when they take enough damage they split into more Fission Metroids, meaning you can end up fighting several at once. Basically much more powerful version of the standard Metroids, you can only damage them with a beam that corresponds to their color. On Hard, too many Wave Troopers spawning can easily screw you over during the Omega Pirate fight. However, there's no easy way to deal with Wave Troopers stunlocking them only works if there's one of them, the Wavebuster is Awesome, but Impractical, and regular shots are very weak. Ice Troopers are quickly dispatched by a charged shot followed by a missile, Power Troopers can be knocked around with Super Missiles, and Plasma Troopers can easily be cut down by the Plasma Beam.

On the bright side, the Super Missile combo works on them, and once you get the X-Ray Visor, they can be tracked when they're invisible.

Durable, immune to everything but the Power Beam, capable of knocking out your visor with their attacks, and they spend most of the time invisible.
