What if the player, Laventon, and Ingo didn't originate from Hisui, but from another region in the future.
Points that add up
Ingo's lines
The Electrode known as the Lord of the Hollow is somewhat different from the Electrode I recall.
I recall, faintly, that I had a partner once. A precious one. Its name escapes me, but I remember that it wielded flames with mastery. If only it were here, I'm sure it would light the way, luring us onward..."
"I'm starting to recall a man who looked... like me. We'd battle and discuss Pokémon, I think... The words "I like winning more than anything else" flashed through my mind just now..."
"Professor Laventon told me how you fell to this land from the sky. For my part, I simply found myself one day here in Hisui, a region whose name I'd never heard... All I could remember was my own name.
"What am I saying? Hidden moves? There are no such things in Hisui, surely... Yet I feel as though I was on the cusp of remembering something just now... Just who was I before I came to Hisui? If you fell from the sky... you come from another world altogether, most likely.
And finally, Raichu's entries from LA and FR
Its electric charges can reach even 100,000 volts. Careless contact can cause even an Indian elephant to faint.
It can discharge bursts of electricity exceeding 100,000 volts—a single strike with that amount of power would incapacitate one of the Copperajah of my homeland.