It depends game balances

1. Touhou has no such thing as cloack
2. Only Hero units have skills (like in SUM(to name an RTS with Hero's and ability's that CAN potentialy be considered OP)
3. Why ballance?... Marisa is match ending already, stop thinking about ballance, just add Touhou. The moment you add Mokou and Kaguya ballance will be dead and forgotten anyway, not to mention some other chars. If at all, add an option for Hero's to be buildable in MP, problem solved.