"Shadow Mewtwo is a regular Mewtwo that has been corrupted by a Shadow Synergy Stone. Instead of being white, it is instead a very dark gray color. Its tail is also dark gray, although at the tip it is tinted orange and has a crystaline texture, due to the Shadow Synergy Stone. The Shadow Synergy Stone that is corrupting it is embedded in its left shoulder (right from forward POV). Besides this it appears to be identical to an uncorrupted Mewtwo."
Right now I can't say how stable the LoRA is. Got the feeling the trainer got issues and also the generator. Some checkpoints seem very wonky right now.