Caught them all

Power slugs are randomly around the world and are bright & glowing - they're pretty easy to spot if you keep an eye out for shiny things. Keep an eye on top of large rocks, and build ramps to get up to them if you need to.

You'll get Yoink! for the first one you find, and then this achievement will unlock when you've gotten all three types.

Note that Blue slugs are easy enough to get - but the others tend to be protected, or otherwise dangerous to get, by things around them; either creatures or aggressive plants or poison gas. These [places become easier to approach as you progress the game.

There are over 1,000 slugs in the world altogether - it won't be hard to find a few of each colour as you play through naturally.