Ryan "Sumo" Sumouski is one of the three main protagonists (More as a deuteragonist) in Clarence. He is one of Clarence's best friends.
Sumo is a scrappy, streetwise kid who grew up on the right side of the wrong side of the tracks. When problems arise, Sumo's solutions are unorthodox and often messy. A wild card and fearless to a fault, Sumo is unpredictable, independent, and often acts without thinking things all the way through. Sumo is fiercely loyal to his friends, and always available. Jeff and Sumo are polar opposites, but Clarence bridges the gap between them. Sumo is the instinctual third of this trio. However in the episode, "Chimney", it is shown that he is quite handy as he is able to build a ladder out of sticks and shoe laces.
Sumo used to have long, brassy hair, but asked Clarence to cut it, as shown in the "Pilot". He currently has no hair at all, except for several strands. He has a big forehead, small, and somewhat crooked teeth, with spaces in between some, and has big eyes and big pupils as well. Sumo wears a black t-shirt, cut-off jean shorts, and dark red boots.
In Season 3, he wears a West Aberdale Elementary uniform, which it consists forest green short sleeve shirt and khaki pants, but Sumo cut them short to look closer to his old clothing.
- Clarence - The two of them enjoy doing lots of cool and fun stuff together. He can also be a bad influence on Clarence sometimes and he will constantly get them into some trouble.
- Jeff - Sumo finds Jeff a bore. Even though they did have fun at Jeff's house when Clarence was away, he still finds him boring. The two of them are friends, but Clarence seems to be the one that glues their friendship together.
- Belson - Sumo hates Belson because he thinks of him as a jerk. He never falls for Belson's pranks.
- Sumo has -5 buddy stars in "Clarence's Millions,".
- Sumo is less wild, and noticeably more smart and serious in "Jeff's New Toy".
- He has a yellow backpack as seen in some episodes.
- In "Rough Riders Elementary", it's revealed that his real name is Ryan.
- Sumo is the only one in the trio that has ears, which Clarence and Jeff lacks.
- Sumo is shown to throw out a punch whenever someone wakes him up. This was shown in "Jeff's New Toy", and again in "Nothing Ventured".
Sumo has 12 siblings; 9 young brothers, 2 older brothers and one sister.
- Sumo finds math and tests boring.
- For some reason, Sumo sometimes flips out while hearing squeaky noises, causing him to distort outlines.
- "Nature Clarence" was the only episode Sumo had a supporting role.
- Sumo sometimes goes crazy and acts like a wild animal in several episodes.
- In "Bird Boy Man", he is the 2nd character to be shown nude.
- First being Clarence in "Goose Chase".
- In "Dream Boat", Sumo's last name was "Sumozski", but however in "Space Race", it is spelled as "Sumouski", while in "Sumo Goes West", his last name is "Sumowski". It is unknown if this is a spelling error.
- Starting in "Sumo Goes West", Sumo no longer goes to Aberdale Elementary, and has started going to West Aberdale Elementary instead. This is due to the mayor drawing a line on the middle of the city map, eliminating Sumo and two other kids from the school.