the EIU (Elemental Imps United) is all the original and most powerful Imps united to have a bunch of fun (though their idea of fun includes destroying cities.) Imps are a race of very naughty goblin like creatures, and in the race there are lots of other species, each one connected to and has the power of a element. Each of the elemental species has one leader which is the most powerful one of them all, and when they unite together they become the EIU, and have a bunch of fun wreaking havoc and killing.
The EIU are extremely hard to control, though Bobby McMuffin once got them in his army to destroy Deedle.
IMPS IN EIU:
There's also Little Imp, a imp created in a lab by Bobby McMuffin out of Imp's DNA.
Imp, the earth imp, is also not only the most powerful of its species, but also the last, since all the other Imps have died out. (pollution and climate change may have something to do with this.)
Meanwhile Yiglet still has an entire species of less powerful yiglets. Yiglets swim in the ocean and latch onto people, killing them and using them as boats.
Impferno also has a whole species of impfernos that live in volcanoes, occasionally blowing them up.
Spasm only has one of its self though, because it was originally just a blank imp (blank imps are imps that have no elements) that had too much radioactive energy drinks and red bull then got electrocuted. Spasm always has spasms and thinks as much thoughts as a normal imp would in a hour in 10 seconds and cannot ever stay still.
Once all the imps combined to create a POWER IMP but Goblin used it to power his rings and sucked a lot of the energy out of the imps, but it eventually grew back. That's how Goblins rings got powers.