Hydro Contaminators (Reflections)

The Hydro Contaminators are a group of aliens that have water pollution-motives.

In the fanfictional series Reflections: A Power Ranger's Story, they serve as the footsoldiers for the Hydro Crew.

Power Rangers Zeo
The Hydro Contaminators attacked Aquitar by dumping poison into its waters. One came to Earth by following Cestro & planned to contaminate Earth's water supply. That Hydro Contaminator was destroyed by the Zeo Blaster.

The Aquitians & the Hydro Contaminators later settled their differences.

Another Hydro Contaminator was seen to receive the Neo-Plutonium Armor but he was not used for battle. It's possible it's the same one that followed Cestro.

Reflections: A Power Ranger's Story
It's later revealed that not all the Hydro Contaminators made peace with the Aquitians. Many of those Hydro Contaminators joined the revived Hydro Hog on his quest to endanger all water-bearing planets, including Earth.