I hadn't realized I past 100 Asks this year, so here's the milestone pic for that!

Copied from the tumblr:
Due to the low number of characters and mechanics, almost any character can perform well. Nonetheless, a tier list has been made based on a variety of play data since Super Smoosh Bros’s release in January 2013.

Tier list:
S-tier, a tier for the most powerful and unmatched character of them all.
Tiny Ray
Its speed is incomparable to the rest of the cast, easily running circles around the other wolves. Tiny Ray’s attacks are weak but really fast and can trap others easily, its recovery is unpredictable and hard to guard, and makes Tiny Ray’s camping abilities top notch. Banned in some places.

S-Tier, exceptional characters who are fantastic picks all around.
Jott
A very small and speedy character who has some surprisingly strong attacks. His agility and small hurt box make him tough to hit, and his Modular Counter gives Jott enough versatility to easily overcome almost any opponent.

Juke
Despite being speedy, Juke is among the heaviest characters in the game, making him tough to smoosh without being smooshed yourself. Couple that with his sneaky plays, Juke gives trouble to almost every big character.

Jutus
Jutus is large, has a high weight, and strong magical attacks with his Money Magic that give him good range. His biggest weakness is having to balance his Money Power, which can drain quickly if the player is not careful. Jutus also has a hard time against Tiny Ray and Jott, two of the most widely-played characters.

A-Tier, a balanced tier fittingly featuring the original three wolves.
Jorkin
Jorkin has many tools at his disposal which works for almost every situation, along with fantastic range. His light weight makes him prime for smooshing if he’s cornered, though, and Jorkin’s tall hurtbox means he’s easy to hit and is prone to missing smaller characters.

Jekiah
Very speedy with the best jump height in the game, Jekiah is considered a very balanced character who has no strengths or weaknesses. Unfortunately, it also means he has a harder time keeping up with the S-tiers, despite having a faster run speed than all of them.

Jack
Jack has immense strength and weight, being able to stay unflattened for a long time. This large amount of stamina comes at a price though, Jack has a hard time even getting hits in on faster and smaller characters, with Tiny Ray being his worst match-up.

B-tier, characters who can win but will have a very hard time doing so.
Juicy Bones
A slimey wolf who has some of the best ground control options in the game but is very easy to punish due to his sluggish attacks. Juicy Bones has a high learning curve but has a niche of being a hard counter to some of the higher tiers, most notably Tiny Ray.

Jotros
Big and slow, Jotros has a hard time with most match-ups due to his bad frame data and predictable moves. Jotros players need to read the opponents well in order to win, with powerful but very slow moves that are hard to land. Jotros’s Love Split helps him against speedier characters, but is plagued with a huge lag time that leaves him vulnerable.

C-Tier, completely nonviable.
The Pillar
The Pillar has the lowest jump and dash speed in the game. He has a hard time against every character, with Jotros being his only 50-50 match-up. The fastest move the Pillar has is his Dash Roller, which has an 8-frame start up and is easy to block. He is also easily countered from his slow and predictable moves.

Lastly, shout-outs to the best Sudden Death I've ever had.