Cilan is one of the Striaton City Gym Leader trio, along with his two brothers: Chili and Cress. Cilan specializes in Grass-type. He gives the Trio Badge to trainers when they defeat him. Cilan's appearance has a similar outfit to a waiter, along with his brothers.
Cilan is the first gym leader to be encountered if the player character chose Oshawott at the start of the adventure.
He's a tall, slender young man with slicked back chartreuse green hair with a four-pointed tuft that sticks up, and grass green eyes. He wears a long sleeved white shirt under a black waistcoat, black straight leg pants, a white apron, and flat brown shoes with golden buckles like his brothers do. He also wears a green bowtie, corresponding with his hair and eye colour, and his choice of Grass-type Pokémon.
In the games, Cilan appears to be rather unsure and somewhat of a coward, but gentle, friendly, and soft-spoken.
Black and White
Cilan is one of the Gym Leaders of Striaton City with Chili. If the player picked Oshawott as a starter, the player will battle him. Like the other two Gym Leaders, he has one of Unova's elemental monkey Pokémon.
Cilan is first mentioned in Striaton City by Cheren in the Trainer School before the player battles him, mentioning he was there before the player arrived. After this battle, the player will find him outside the Gym. He invites him/her inside the Gym, getting ready for the battle. Once he/she arrives, however, he reveals his two brothers: Cress and Chili, who are also Gym Leaders and states one of them will battle the player depending on his/her starting Pokémon. He only battles trainers who own an Oshawott. After this battle, the player doesn't hear from him again until after the end of the game when Bianca mentions that she tried to get the three Striaton City Gym Leaders to help against the sages inside N's Castle, but was too late. Cilan will always stay in the gym no matter what version afterwards.
Black 2 and White 2
In Black 2 and White 2, he's no longer a Gym Leader. If Memory Link is used, it is shown in a flashback that the trio begin to question their strength after being unable to battle Team Plasma, as general opinion is that it needs the three of them to make a good trainer, and discuss what needs to be done to correct that. Suddenly the Shadow Triad assaults them on a "whim", and both sides engage in a Battle. However, the Shadow Triad easily defeats the Gym Leaders, which makes them leave so as to check on the other Gym Leaders that can be a true threat. The humiliating defeat makes them admit that they can only succeed as a trio. They then decide to resign as Gym Leaders and restart their training from scratch, so that eventually one of them can become a recognized trainer, then when their strengths match each other again, they can be a trio of Gym Leaders once more. They then think on who will be the new Gym Leader.