Here's the Clan information for all three of the Clans. Read this before making a cat.
FrozenClan - Harsh and Strong
FrozenClan lives high up in the snowy mountains. They are both strong hunters and fighters. The mountains have scarce amounts of prey so that is why they value good hunters. They are not ruthlessly violent, and do not fight unless they think it is necessary. However they are very protective of their territory and will harshly fight trespassers. They respect and value medicine cats, because even though medicine cats do not fight, they are very useful because they heal injuries and wounds. FrozenClan cats are very loyal to each other and cats who break the rules within the Clan are punished. Weak cats are usually not very respected and are cared about less. Leaders do not choose deputies, instead when a deputy dies (or the leader dies and the deputy becomes leader and therefore needs a NEW deputy) the cats who want to be deputy fight eachother for the position. Cats who lose fights are not killed, but instead forced to leave the Clan.
TreetopClan - Intelligent and Swift
TreetopClan cats live in a forest of very tall trees, and do all their hunting in the treetops. They are very fast and are not accepting of cats who are bad at climbing or running. Sometimes, cats who lack those skills are even kicked out. TreetopClan also values medicine cats because in the forest diseases are common so medicine cats are very useful and are also honored for their wisdom. In TreetopClan whenever a new deputy is needed all the cats who want to be deputy compete in a contest of hunting, climbing, running, and wisdom. Whoever wins gets to be deputy and the losers do not have to leave the Clan.
SandClan - Laid-back and Chill
SandClan lives on a beach by the sea, and prey comes easily to them. They are very laid-back and not serious, and live pretty easy and lazy lives, sunning themselves and taking lots of naps. They are pretty friendly and don't protect their territory much. In SandClan leaders just choose their deputies. SandClan cats do get injured a lot on the rocks while fishing, and diseases are also not too uncommon in their territory, so medicine cats are respected there too. The medicine cats are probably the most talented and smart cats in the Clan. Actually, they might be the only talented and smart cats in the Clan. Even though SandClan has great medicine cats, they don't fight at all, and so they would be the most vulnerable to any threat other cats pose to them.