Delta Krabby & Kingler Story-
How this form of Krabby came about was to a group of Krabby and Kingler moving deeper into the sea looking for food and shelter. They set up a home near underwater volcanos and over time lost the water typing to favor their new home, Fire/Rock and later to Fire/Steel. Despite now being four times weak to water in typing, they gained the ability Dry Skin from living near the active underwater volcanos. They still can be found having the Hyper Cutter ability and in some rare cases are found with Solid Rock (Hidden Ability). Some of the new features gained from their new habitat are the spikes found on the tops of each pinscher and the vent-like holes found on the backs. The spikes serve as a tool when climbing or fighting by backhanding their foes. The vent-like holes on their back act as a way for the Pokemon to cool off as they produce a great amount of heat. It is said that once you get past the tough outer shield the meat inside is amazing.
Delta Krabby- 
Type: Fire/Rock
Category: Sea Vent Crab Pokemon
Abilities: Dry Skin/Hyper Cutter
HA Ability: Solid Rock
Dex Entry: Delta Krabby hunt by letting out a cloud of smoke to then rush their prey striking with the spike on the back of their pinscher. They stick around sea vents to cook their prey.
Delta Kingler-
Category: Volcanic Crab Pokemon
Type: Fire/Steel
Abilities: Dry Skin/Hyper Cutter
HA Ability: Solid Rock
Dex Entry: Delta Kingler are able to heat up their large claw to a high temperature melting anything that is caught on the other end. With the vent-like holes that are placed on their backs, they can shoot out a large amount of smoke to push them wherever they are facing.
(I only have the PC sprites I have made for them. Would LOVE to make full sprites but my skills wouldn’t do them justice.)
P.S.: Feel free to give your Shiny Ideas.