Fakemon based on Hydrothermal Vents - What type works better?

[TreadingWater]

I recently came up with my region's rock-type which is based on hydrothermal vents as well as crustaceans (since they are some of the few animals that lives in that environment), and at first I was thinking about making it a Rock/Water-type (with an ability to compensate for the dual weakness to grass).

But I realized that I already had an overabundance of water-types already, so I was wondering what kind of other types would work for this concept.

 

[Eurritimia]

i do think that thematically rock/water works for your pokemon, but if you're too worried with too much water, maybe your pokemon should be rock only.

 

[wrigty12]

A cool thing to consider is a type combination that wouldn't necessarily fit the creature it's based on in the traditional sense. When I read Hydrothermal Vents, obviously water comes to mind. However, what about the "thermal" part? A Rock/Fire crustacean?

 

[Grass]

Building on what the above user has said I think a rock/fire type would fit really well. It could be physically bulky but with a high special attack and moves like scald for coverage. This might end up being too similar to Coalossal.

It could also be a regional form of Crustle/Dwebble.

 

[TreadingWater]

Building on what the above user has said I think a rock/fire type would fit really well. It could be physically bulky but with a high special attack and moves like scald for coverage. This might end up being too similar to Coalossal.

It could also be a regional form of Crustle/Dwebble.

I have already a design sketched out that I really like, so it is not going to be a regional variant.
It is closer to the Roggenrola-family, but is still its own thing. It having Scald was a given for me and I am also planning on giving it some Poison-moves given that hydrothermal vents releases a lot of toxic elements such as sulfur into the water-column. I am not sure if the Rock/Fire-type would work because they actually live at the bottom of the ocean, wandering down there once they fully evolve in the wild as they are barely able to support their heavy bodies on land.

An idea that I had for it in order to work with a potential pure rock-type was to give it an ability that weakens the power of grass and water-moves, given that extreme heat boils water and makes plants wither.