First up in my new line of Fakemon for my own region, the tropical Kilida region, is the Water/Steel Deep-Sea line. If the Kilida Region had its own games, they would be Acai and Plantain versions.

Haxetfisch
Hatchet Pokemon
Water/Steel
Acai entry: The deep-sea dwelling Haxetfisch goes most of the day without eating. At night, it swims to the surface to feast on bioluminescent plankton and fallen berries.
Plantain entry: Its eyesight is extremely sensitive. It cannot see anything in bright light and if battling above water during the daytime, it has to fight blind.
(Can only be caught at night)

Laceropheus
Blade Pokemon
Water/Steel
Evolves from Haxetfisch at level 37
Acai entry: A ferocious predator, Laceropheus preys on Pokemon like Lanturn and Malamar in the icy depths of the ocean. It very rarely surfaces, so many mistake it for a mermaid.
Plantain entry: Its eyesight has diminished and it now senses prey using heat signatures. It is incredibly fast, giving it the title "Scyther of the Sea".