Ado is a character from the Kirby series with human like qualities, the only one of that type who lives on Pop Star. She's a painter and first appeared in Kirby's Dream Land 3, where her appears as the boss of level 4. During the fight, she'll paint four different bosses that'll come to life and fight the pink protagonist Kirby, including Ice Dragon, Sweet Stuff, Mr. Shine and Mr. Bright, and Kracko. Once she defeated all of those bosses, Kirby would then be required to take on Ado. This, however, is not a chore, as one hit will take Ado down.
In Kirby 64: The Crystal Shards, there is a character named Adeleine who is very similar to Ado in appearence and powers. Its very likely they're the same character, since Adeleine's japanese name is "Adoreenu", making "Ado" the likely nickname for her.