Not shore how to word this. It may be a two fold question on the identity of the Dark God.
Firstly is Megalothor it's own entity. The events of episode 8 & 9 strongly hint that yes the Dark God is it's own monster to me. It seems to be the physical form of the Dark Energy itself and is not just an extension of Carmeara. Had anyone else tried to clame the power of the Eternity Core, Megalothor would have formed regardless, though may the first from would have looked differently.
Second is it an "It" or a "She" when separated from Carmeara. Megalothor is always referred to by the "It" pronoun as far as I can tell, and it's title of "God" is generally used either neutrally or masculinlly. Most Ultra monsters are likewise referred to as it if no gender is stated at all and we are talking about a lovecraftian deity in Ultra Monster form so to me "It" is very fitting to such a being.
Sorry if this is a silly or weird question.