How do you catch horsea in ruby?
you have to get all the Pokemon in kanto trade them and go to a contest hall beat all the contests and you will get a ferry tiket to
In HeartGold or SoulSilver: Catch a wild Seadra, Dratini, Dragonite, Horsea, Dragonair, or Kingra holding the item. Or successfully find and catch a Horsea in the Winner's Path PokeWalker route. In Diamond, Pearl, and Platinum: Catch a wild Dratini, Dragonair, Seadra, or Horsea holding the item. In FireRed and LeafGreen: Find one on the Water Path. In Ruby, Sapphire, and Emerald: Catch a wild Horsea or Bagon holding the item.