Darius - he's pretty tanky so he lasts long in a fight, and he can deal some heavy melee damage.
Kennen - hits pretty hard, not as hard as some mages granted, but he's also got an aoe stun which will lock up the entire team plus really good suvive with his ball and stun.
Teemo - hits like a truck...has shrooms which help scout and soften up enemies before fights begin.
Jax - stun, good survive, hits hard, can be build ad or hybrid which makes him versatile in game
Overall, Bruisers dominate this map. Assassins i feel are more situational (to counter things like teemo for instance), and mages trump adcs because they have higher burst as opposed to sustained damage. Burst is better in this map since you're more likely to die quickly there being only 3 players so you need to get your damage out faster since the fights are faster.