Ignoring how bad the battle was, since apparently Ash cheated.......oh sorry the writers decided to purely use ANIME only mechanics to allow Ash to win this battle.
Can we talk about how cool it is, that apparently (based on the images), Ash (or Pikachu) was allowed to actually choose a Z-crystal for winning. That I think was at least the best part of the episode, that I could see.
Anime mechanics or not, there should've been NO WAY that would've worked.
Why?
Water/ground type Pokemon EXIST. There's no reason to believe that a Pokemon "naturally soaked" would've somehow overridden an existing type.
There is a reason why "Soak" is a Pokemon move, or in fact in reference to an ability. It makes sense for a Pokemon move to temporarily override a Pokemon's type, since the entire "soak" move is about oversaturating the Pokemon with water so it becomes the water type.
Don't think it's "fair" to argue a ground type taking a swim qualifies it as a water type and therefore weak against electricity.
Especially with a Pokemon like Stunfisk, which has to SPECIFICALLY use camoflauge to actually change its type.
This, is just a stupid justification for a stupid outcome for a stupid battle, because they either didn't want to give Pikachu Splishy Splash and because they insist on shoving Pikachu down the viewer's throats as per usual, but not in any meaningful way, you know like it's specialized Z-move, what we can't get a story about that? We have to deal with it being used constantly with no reason then they have nothing better to write about.
It's getting annoying, and I only tolerated it SOLELY because of its exclusive Z-move, because I thought it was REALLY neat that only Ash's Pikachu can use its exclusive Z-move, as it was made just for them. Instead we get Gigavolt Havoc after another, and just unnecessary Pikachu focus for no reason other than because the writers are incapable of writing for the other Pokemon (possibly), or they just care (which I'm leaning towards to, given how the series has been portrayed as a whole).
So I take it Nanu is Ash's best Grand Trial, maybe tied with Olivia? Because this wasn't even anything but a random episode, where Ash gets a steel type z-crystal.