There's some sort of hierarchy in Briar's team and they interact based on that...

Talonflame is considered by the others as the leader of the team, not only because he's Briar's ace but because he has a very responsible and respectable personality! Houndoom is considered the right-hand-man or second-in-command, he's also the brawn or the muscle of the team because, unlike the rest, he was actually trained with Pokémon Battles in mind. Charizard is the third on the list, because despite not being a very great leader or a super intimidating Pokémon, he's one of the oldest members in the team so they respect him for that... He's the brain of the team hehe. These three are part of Briar's original team in Kalos so they're the big three, the "Victory Trio".

The rest of the team (Chandelure, Volcarona and Nickit) are not part of the "Big Three" so they're more like followers. Although Nickit got a reputation of her own because despite being the youngest, her spoiled and princess-like personality lets her get away with everything bad she does lol When she causes mischief and makes someone else angry, she goes to Houndoom and gives him puppy eyes so he protects her from any Pokémon LOL