Cerulean[from internal data] is an enemy in Kirby's Return to Dream Land and Kirby's Dream Collection. It is found in Raisin Ruins and Nutty Noon. It is very similar to Pteran from Kirby's Dream Land 3 in its role and how it flies. It provides no Copy Ability if swallowed.
Kirby's Return to Dream Land
Found throughout the Raisin Ruins and Nutty Noon levels of Planet Popstar, Cerulean is known for flying slowly in short bursts in predictable patterns. It is not actively aggressive, but it will still hurt Kirby and other characters by contact. If it comes into contact with a wall, it will change direction. While not very dangerous on its own, large flocks of Cerulean will often be seen high in the air, occupying empty space and discouraging Kirby from trying to fly out in that direction.
Kirby's Dream Collection
Cerulean can be found in New Challenge Stages, in the Fighter Combat Chamber and Magolor Race 1 and EX. It is practically the same as with the previous game in terms of behavior and as such, it can leave the arena, which is a bad thing if Kirby is aiming for Platinum.
Kirby: Planet Robobot
Cerulean returns in Kirby: Planet Robobot primarily in Gigabyte Grounds. Due to the main gimmick of the 3DS Kirby games being centered around foreground-background travel, Cerulean gains a new attack in the form of switching between the two planes in its usual lethargic patterns. Additionally, they still give no ability when swallowed by Kirby.