Builds??

I mean the body types.....big, small, mucular....that

I think of their build types based on their environment and diet. So, I see it like this.

ThunderClan live in dense forest with lots of brambles and briars, tons of trees, and have to be strong to catch the prey found in the environment. So, I see ThunderClan with mostly dense fur, strong legs, more set towards the ground, broad shoulders, and longer claws. They also climb trees, so I see them with strong back legs.

ShadowClan lives in a more swampy area with a lot of pines, if I recall correctly. ShadowClan are specifically known for their stalking, so that means their reflexes have to be sharp. So, I can see them with longer legs, light and airy, built for stealth, and shorter fur. They're going to need sharper eyes, and a long tail helps with balance. Considering that they also eat frogs and scaly lizards, they're going to need stronger teeth to tear through the hide.

WindClan almost exclusive chase down their prey until they catch it, so they'll need a lot of dexterity and speed. They wander through pretty tall wheat fields, as well as typical taller grass in a plains-like environment. So, I see them typically with the longest legs of the clans, with a small wiry build built for speed moreso than endurance, due to their environment. Smaller heads, more narrow shoulders, very short fur, and claws designed for faster kills. Larger ears would also help with tracking down their prey through the vast fields.

Riverclan have the most advantageous environment, with fish being readily available the majority of the time. They have to swim, so buoyancy and fur length would impede this. Therefore, I see RiverClan as all incredibly well fed, with legs closer to the ground for easier fishing. for what they hunt, long claws would be the most advantageous, and while I see them all rather hefty, longer fur would be a problem for them in deeper water. Larger heads would also guarantee a higher chance of catching the fish.

SkyClan are a hodgepodge of cats who joined not too long ago. So SkyClan's typical build would not be as easily determined. What I do think all cats would have some semblance of, would be incredibly strong hindlegs.

The Tribe live in a harsh environment, and I don't imagine they're all that well fed. They'd all have to be pretty lean from the sheer exercise they put into just hunting food, and they're have to have very strong back legs with great balance to actually leap to where they need to go. Since they live in such a harsh environment, longer fur would be advantageous.

So, to recap:

ThunderClan: Broad shoulders, longer claws, thicker fur, strong back legs, well muscled, not that tall, about average
ShadowClan: Long legs, light paws, sharp eyes, well muscled, shorter fur, long tail for balance, strong teeth
WindClan: small, long legs, large ears, small heads, wiry builds, narrow shoulders, very short fur
Riverclan: Shorter legs, long claws, well fed and more heavyset, short fur, larger heads,
Modern SkyClan: Would all need longer tails for balance and strong back legs
Tribe: Smaller, lean builds, strong back legs, exceptional balance, longer fur