Momotaru was the courageous sailor who fought against the Higemaru pirates in Pirate Ship Higemaru and Higemaru Makaijima.
Decades later, he was considered as a playable character for Street Fighter V, but was rejected in favor of Birdie. His SFV website profile states that he did pick a fight with Ryu at some point, though.
The antagonist of Pirate Ship Higemaru (Bows), the long-dead pirate legend from Higemaru Makaijima (Beard), and the pirate from Marvel vs. Capcom 2 (Ruby) became his siblings in his SFV profile. These pirates became regular sailors in the new retcon.