"My problem with fish Pokémon"

I realize this is a ridiculous thing to be annoyed by in a game where 10 year olds have obscenely powerful magical creatures and can literally control the god of the universe, but something that has bothered me for literally years is how "fish Pokémon" behave in battle/on land. These ostensibly UNDERWATER creatures can somehow "swim" through the air when battling in places nowhere near a body of water. Now I totally understand WHY the games are designed this way, as fish Pokémon would be essentially useless 99% of the time otherwise, but it drives me crazy that there is no explanation that I've ever seen as to why if fish Pokémon DO have this capability, they are still only encountered in the water. The only rationale that I've come up with is that the Pokéball grants them this ability upon exiting it (because science), but as with most things in the Pokémon universe, I'm assuming there is an explanation somewhere that I've missed, despite having played through every generation at least once. If anyone is aware of what this explanation is, I'd greatly appreciate you letting me know, as it may keep me from getting annoyed every time I encounter one in-game.Even worse is that the only fish Pokémon who behaved as you'd expect when battling on land is fucking Magikarp, flopping about like an actual fish out of water... but then in Let's Go, it has the same goddamn animation while in the water! What the fuck Game Freak?! You spent all this time on putting Pokémon in the overworld, but couldn't be bothered to give Magikarp a separate swimming animation?! via /r/pokemon https://ift.tt/2BQrAtT