Pokemon FQIQ - Swamp Hippopotas and Hippowdon

Texxalan Hippopotas - Though Hippopotas have been know to inhabit the deserts, they still need water. Toxic chemical spills, contaminating the water supply, caused their physical chemistry to change, resulting in strange mutations. Because of this, they have been forced to move into toxic swamps, where the contamination has concentrated. Hippopotas began feeding on the toxic grasses that grew around these swamps, causing it to begin growing these same grasses on it's back and nose. Unlike the Ground-type variant of Hippopotas, the Texxalan form takes in massive amounts of chemicals everyday, resulting in it becoming a Poison-type. Because it needs a place to store these chemicals, the sand spouts on its body have sealed up, to keep in various poisons. Though it cannot survive extremely heated environments like it's counterpart, it is incredibly toxin resilient, and can survive under the water without breathing for as long as 2 hours.

Texxalan Hippowdon - Hippowdon, evolved from the Hippopotas that have matured in toxic wastes, are bigger than normal and can be much more ferocious. Texxalan Hippowdon are the largest Poison-types in recorded history, and are not typically found with a trainer. Now it produces toxins all on its own, like a living chemical factory, all of which conglomerate inside the the mucus sacs that are strewn across its back. Because of this it is a major contributor to the toxicity of the swamps it lives in, sometimes changing the chemical composition completely, resulting in toxins staining its coat when it wades through water. Texxalan Hippowdon are extremely territorial, and fight not only people and Pokemon, but each other for control of the swamps. The one that controls the main toxin flow is usually the one with the biggest tusks, resulted from the extra chemical intake.