Suggested by Sonic Tidus is a Final Fantasy main character so you can probably guess that he’s really strong. That being said, Poseidon still has the edge here. He has power on the level of a Gold Saint and Tidus won’t have any real way of getting past his armor. Poseidon can just keep on repelling his attacks and that will be the end of that. There just wouldn’t be a way for Tidus to dish out any meaningful damage. Poseidon (Saint Seiya) wins.
Poseidon (Saint Seiya) makes his debut alongside Delphinus! Both of them are water type fighters, but there can only be one winner in this battle. Poseidon definitely outranks Guney in this battle, but you may have already guessed that based on the name. Maybe Guney will be back someday. Poseidon (Saint Seiya) wins.