The current meta for the Kingdom Arena in Cookie Run Kingdom is filled with epic cookies only, as to be expected. For a while it was Dark Choco Cookie and Milk Cookie as tanks, but it's since then shifted to the following five cookies:
Kingdom Arena cookie meta (February 2021):
Dark Choco Cookie is arguably the most powerful tank right now. Not only does he absorb a lot of damage, he does a decent amount of damage too. That's the not the real reason dark choco cookie one of the most overpowered cookies in Cookie Run Kingdom however. His knockback ability is extremely powerful, and is very effective at keeping enemy melee cookies from hitting all cookies with area of effects, as is the case with werewolf cookie.
Espresso cookie arguable the most powerful or second strongest cookie in the game right now. She does massive guaranteed damage to all enemy cookies. That's not all that makes her strong however, she also groups all enemies with her attack, which makes them vulnerable to area of effect attacks. Not only that, but doing this temporarily reduces damage from enemy melee units since it continuously pulls them away from your front line cookies.
Licorice cookie is tied with Espresso cookie as the most strongest cookie in the game. She temporarily increased everyone's defense, but more importantly, she summons 3 minions that eat massive amounts of damage from the enemy team. It's also noteworthy that these minions do a surprising amount of damage. Because of this Licorice cookie fills both the roll of a damage dealer, and a tank at the same time.
Herb Cookie is hands down the most powerful healer in all of cookie run kingdom. The reason he's so much better than all the other healers is because he heals in an area of effect that heals percentage of max health. In the right scenario herb cookie heals multiple times more HP than any other healer or support cookie.
Vampire Cookie is the newest addition to the meta. He does a lot of damage, but what really makes him one of the best cookies in Cookie Run kingdom is his natural life steal. Because he has life steal he can effectively act as a tank when the battle comes down to the final cookies. If the enemy only has tanks left then there's a good chance vampire cookie can outlast them with his life steal.