>>38545257>Are purely water dwelling pokemon at an disadvantage in battle?IRL 'Pokemon World' ? Yes. Absolutely.
Purely aquatic Pokemon are at an enormous disadvantage against basically every terrestrial or flying Pokemon so long as it's a battle on land or what have you, but then the obvious trade off is these Pokemon's ability to fight in water uninhibited.
Realistically if you wanted to specialize in competitively viable water-type Pokemon you'd need to exclusively train amphibious water Pokemon like Blastoise, Polywhirl, Slowbro/King, and Azumarill, n' so forth. Unless -in this hypothetical situation- you only plan on devoting yourself exclusively to the sub-culture or class of Trainers whom ONLY fight and battle on the water. Which I'm sure there'd be, because that sounds like it'd be SUPER fucking interesting- battling, training, and specializing in purely aquatic Pokemon that is.