on route 226
catch a horsea evolve it into seadra give it a dragon scale and trade it
Catch a horsea or seadra and put the item on seadra (evolve horsea) trade it with someone else and seadra will evolve into kingdra
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.
you can catch horsea in ocean current with fishing.
seadra
When you trade it holding a dragon scale.
in jungle relic at water challenge
kingsea is not a pokemon. if you are looking for horsea, seadra or kingdra, catch a horsea in whirl islands, evolve it into seadra, and trade it with a dragon scale
During trade it must hold dragon scale to evolve.
some are seadra, sealeo,and lantern. But you can pretty much catch any thingGyrados, Seaking,you can even catch a tetnacruel
You can catch a Seadra in the wild at Dragon's Den or evolve a Horsea into Seadra via leveling up while holding a Dragon Scale. Finally, you can evolve Seadra into Kingdra by trading it while holding a Dragon Scale.
to get seadra you can find it at whirl islands or get a hoursy which is also there. to get in to whirl islands you need the hm whirlpool. whirl islands is around the coast of Cianwood city in root 41.