This is a Tier List going over all of the champions on the Twisted Treeline 3v3 map - Patch v18.104.22.168 (Hecarim Release).
Tier 1 contains incredibly strong champions that have the ability to carry games and excel at multiple things such as teamfighting, jungle control, mobility, and laning. These are generally the most banned champions.
Tier 2 contains a strong group of champions which include those who may be picked to counter other Tier 1 champions and are strong against most picks in general. These champions fullfil their roles well and excel at a certain job, typically laning or mobility.
Tier 3 is an array of above average champions who are generally stronger than the lower tier champions and can perform their jobs well. Each of these champions can still be a strong pick, but have more weaknesses than those in Tier 1 and 2. Be aware of these champions as they are still generally solid picks depending on team composition and laning matchups.
Tier 4 is consists of average/sub-par champions who can still be a threat, but do not provide anything extraordinary to the table. Each of these champions generally require help to perform their role successfully and are somewhat gimmicky.
Tier 5 is what it is, the lowest tier. Each of the champions in this tier do not scale well in terms of 3v3 and are just completely outdone by another higher tier champion. As a 3v3 enthusiast who tries new things, I think every champion is viable and works well with a strategy, but each of these champions can be and usually are outclassed by others. Be aware that some of the champions in this tier can hard counter higher tier champions throughout the game.
(in alphabetical order)
* - Scroll down for explanation and analysis of these champions.
TIER 1 - Gangplank, Jax, Lee Sin, Lulu*, Singed, Tryndamere*, Udyr, Yorick, and Evelynn oops.
TIER 2 - Akali, Cho'Gath, Jarvan IV, Kennen, Morgana, Nidalee (AD), Nunu, Pantheon, Poppy, Rammus, Renekton, Riven, Rumble, Shaco, Shen, Shyvana, and Wukong.
TIER 3 – Ahri, Amumu, Caitlyn, Cassiopeia, Corki, Dr. Mundo, Ezreal, Fizz, Garen, Galio, Graves, Hecarim*, Heimerdinger, Janna, LeBlanc, Malphite, Mordekaiser, Nautilus, Nocturne, Olaf, Orianna, Sion, Skarner, Soraka, Swain, Talon, Teemo, Tristana (AP & AD), Twitch, Urgot, Vayne, Veigar, Vladimir, Warwick, and Xin Zhao.
TIER 4 - Alistar, Anivia, Annie, Ashe, Blitzcrank, Brand, Fiddlesticks, Fiora, Gragas, Irelia, Karma, Karthus, Kayle, Kog'maw, Leona, Lux, Malzahar, Master Yi, Nasus, Nidalee (AP), Ryze, Sivir, Trundle, Volibear, Xerath, and Zilean.
TIER 5 - (the rest) - Evelynn, Kassadin, Katarina, Maokai, Miss Fortune, Sejuani, Sona, Taric, Twisted Fate, Viktor, and Ziggs.
Note - Tier 3 & Tier 4 contain most of the champions because I feel all champions are viable. It's hard to put champs in Tier 5 even though some of them are very strong in Summoner's Rift. I'm not saying any of these champions are bad picks, they just require certain strategies and team compositions.
Lulu - She's an amazing harassing champion and is capable of extreme turtling/defending a well as outrageous long range poking damage. She can keep anyone on her team alive through just about any teamfight, and provides massive CC + a movement speed steroid. She has a great laning phase and is just in general, a strong champion.
Tryndamere - He is counter picked by Udyr/Lee Sin/Jax in lane, but amazing against just about any other matchup. He is one of the biggest pains to deal with in lane. He has infinite sustain and can spin away to gank/take jungle on a regular basis. Make sure to pick a mobile champion against him or have an attack speed/movement speed slow on your team (Nunu or Lee Sin).
Hecarim - He is the newest champion in the game and I haven't had a large amount of experience with him. I feel he is suited for Tier 3 because he has some strong points, but other champions still out-do him in my opinion. With the right team composition in the right lane I think this champion can carry very well. His only downfall in my opinion is the AP scaling on his Ultimate/W, he lacks base damage on his abilities for the most part.
Note - There will be more explanations for other/newer champions in the future, this is just v1.0 for me. As new champions are released and more changes arrive, this list will be regularly updated accordingly with reasoning.
I hope you all enjoyed the Tier List and please feel free to leave me any suggestions, ideas, or point out things I've missed. I'm open to any of these, just as long as you don't flame me :)