Pokémon Ruby and Sapphire/Route 124

Wild Pokémon
Tentacool, Wailmer, Wingull, Relicanth, Pelipper, Magikarp

Relicanth is found underwater in Route 124 in Pokémon Ruby and Sapphire. Though it is a fish Pokemon, it cannot be caught with a fishing rod. It is slightly tough to catch; 2 or 3 Ultra Balls might get wasted, and Net Balls and Dive Balls do not work well.

Along with Wailord, Relicanth needs to be present in the your team to remove the seals from the hiding places of the Legendary Pokémon, Regirock, Regice and Registeel.