These three Elves are minor antagonists appearing in "Beanie Get Your Gun".
Their leader is the elf with the brown hair, who remains unnamed in the episode. He names the other two "Zippidee" and "Dooh-Dah", but these might be nicknames since they don't follow the usual naming convention of male Elves, whose names all end with "o".
They encounter Prince Derek in Elf Alley. When Derek tries to talk with them, they steal his crown. Derek doesn't fight back, which only angers them more. Their leader orders Zippidee and Dooh-Dah to baralize Derek, but is reminded they no longer have a barrel as they traded them all for crates. Derek however volunteers to just pretend to be in a barrel, and the trio rolls him down the alley and out of the city.
When Derek returns riding the Psychotic unicorn, he passes by the trio and the unicorn takes Dereks' crown back for him.
They appear again in "The Goo-Bye Girl", where they beat up Derek and Jasper with a wooden board when the two boys return home from school, but the two later return the favor with help of Freckles and Snarla. In the fight, Derek ends up hitting the leader of the bullies so hard he seemingly kills him. However, it turns out the three were actually being payed by Freckles to harress Derek and Jasper, and the leader only pretended to have been killed so Freckles could use Derek's guilt of what he had done to trick the boy into running away from home.