Name: Rivercloud

That's a pretty name. I like it.

Age: 20 moons

Still quite young.

Clan: Riverclan

I feel like RiverClan is used most, like Seawings for wof, but they're cool, so I'm fine with that.

Rank: Warrior

Makes sense.

Gender:Male

Oh my stars it's another one.

Personality: Sweet, loves to play with kits, loves to joke around, can get jealous easily.

Sounds good. I like that you added the jealousy one. He sounds like a big softie.

Appearance: Gray tabby cat

A bit more might be nice. But it doesn't really matter. Eye colour, is he tall, muscular, any specific marking, etc.

Abilities: Skilled hunter

Thank goodness you didnt say anything like mind reading.

Likes: fish(favorite prey) Swimming(he's a Riverclan cat) Playing with kits(it's fun and no one can resist kits)

True dat.

Dislikes: arguments within the clan(wants everyone to get along) winter(can't hunt in the river or eat fish) Windclan

Ooh, why doesn't he like WindClan, hmm?

Fears: Storms(reminds him of his brother's death) losing his friends and family(he already lost his brother and father) Windclan(killed his father)

That would explain it.

Backstory: Riverkit was born to two famous warriors, Storm watcher and Slivercloud. He has a brother named Rainkit. When Riverkit was four moons old he and Rain kit went to explore the river when a strong storm came. Because of the strong winds Rainkit fell in the river and was unable to get back on land. Ever since then Riverkit has been afraid of storms. When he was eight moons old his father died in a battle against Windclan. Silverpaw a friend of his helped him in getting through his father's death.

I'm glad Silverpaw helped. This is a pretty good warriors backstory, perhaps a bit cliche, but honestly every warrior or wof oc is cliche. I like it, but some more details about him personally would be good.

Family: Stormwatcher(Dad: diseased) Silvercloud(Mom: Alive) Riverkit(bother:diseased)

Alright.

Other important cats: Silverpelt(used to be Silverpaw. Rivercloud's mate)

Oh , so he and Silverpaw became mates. I seeeeee...

Anything else: I don't think so.

Okie.

Overall score: 8.2/10

There's nothing really wrong with it, it's good, but some more depth would be nice. He had kinda a traumatizing youth, seeing that more in his personality ir traits would make him more transparent. Good job!