Metroid Database Bestiary

The Space Pirates have begun to use an experimental energy grenade launcher in the field. The weapon is viewed as a mixed blessing to the Grenadier units: while the grenade launchers are powerful weapons, Grenadiers must leave their rifles behind to carry them. Fast-moving targets can close range on Grenadiers, rendering their main weapon somewhat ineffective.

These pirates' grenade launchers are dangerous from afar, but they're pathetic at close range. Doing so causes them to revert to melee combat, which they are not very good at. Get in close and shoot a few Charged Power Beam shots in their face to make short work of them.