Yes, PROTEUSES is a Scrabble word!

Letter values in Scrabble US: P 3, R 1, O 1, T 1, E 1, U 1, S 1, E 1, S 1.

Is it a valid word?

PROTEUSES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

(Greek mythology) a prophetic god who served Poseidon; was capable of changing his shape at will
type genus of the Proteidae

Also: genus proteus.