Which cats are training in the Dark Forest?

If you are talking about Warriors then id say cats who murder others and don't regret it, cats who try to become all-powerful while killing others in the process and cats who don't believe in Starclan and are bad

Swifttail-they don't have to believe in starclan. cloudtail and mothwing don't believe in starclan. It doesn't say in the warrior code that you have to go to believe in starclan.