I've been requested to do another Oc, and the harshness was hard. Let's do this.

Name: Moonshadow
Moon used in a name is a bit iffy seeing as I've only seen one cat with Moon in their name. And that was Moonflower, Bluestar's mother. But meh, unique name!

Gender: Tom
Points to you for making a tom Oc. Maybe this world won't be flooded with She-cats after all.

Rank: Warrior
Okay.

Age: 19 moons
So he's a really young/newly made warrior. This is rather common, so you might want to make him older.

Clan: Shadowclan
Alright, we have a stealthy ninja cat on our paws.

Looks: His fur his all black with one red eye and the other eye is black
W-What? How? *Deep breaths*
You chose hard so I'm going to town on this. So let's talk about eye color...Cats do not have black or red eyes. They may have like possibly a orangish eye or something I'm not certain but I know for sure that cats do not have black eyes. It's just not possible. So that's honestly...Nope.

Personality: Cool and nice,sometimes loyal and protective
I don't see any faults in his personality. You should add some things that he could work on, otherwise there's no room for character development. Perhaps weary, to flirtatious, anxious, cold, above others complex. There's many things.

Backstory: Born in shadow clan but he doesn't remember his parents since they died when he was born
Common and bland. There's nothing to this backstory besides the fact that he grew up as an orphan. You didn't add anything else. It's like I'm eating an angel cake without any whipped cream or strawberries. You need to spice it up! Plus without parents you'd think he'd be bitter or reserved. Possibly shy. Not just this perfect personality.

Strength: Climbing,fighting and the darkness
By darkness do you mean stealth? The others are okay.

Weakness: Temper
This doesn't even out his strengths, or go with his personality. You never said that he had temper problems or anger issues.

Fears: Losing anyone close to him
Common fear, and no slack is cut for this character because there's no other flaws. I mean yes this is a common fear and my characters often have it, but I give them more than just one.

Crush: Open
Okay, he's still young.

Mate: Open
Again he's still young.

Kits: (600!!! Lol jk) None
600 would be impossible seeing as he has no mate unless they were a bunch of one night stands. Anyhow it was just a joke, but that is impossible anyway XD.

Finial Results:
Martystuness: 67%

And the cat you got was purely fictional and fake. Because there is no way in heck that there is a cat with one red eye and one black. Your backstory is also very lacking and basic. Not to mention common, just like his age. The fears and weakness also do not match his personality or even out his strengths. So there is basicly zero, zip, zilch, nada character development that can be done with this character.