This is bs and you know it.All an opposing trainer needs to do is use a ground type Pokémon and Pikachu can get beat it’s not hard to make a battle where Ash can lose be believable without having to nurf him
Battle wins are always decided by Plot. Concepts like Type advantages are silly arguments.
The current Plot dictates Ash is an OP Battle experience with an OP rat that bested the strongest trainer owned Pokemon in the world.
At this Point, to make Ash lose convincingly, they'd have to pull a Dragon Ball Super.
Ash at this point is Goku with Mastered Ultra Instinct. Only difference is that there aren't the Angels or Grand Priest (Other characters who are stronger than him). At this point they'd have to keep introducing new characters and randomly make them extremely OP to allow Ash to lose convincingly. So basically current Ash is Mastered MUI Goku that beat Jiren (Leon). Moro, Granolah & Gas will be the new Paldea Champions who trivialize MUI Goku.
Then comes Cameron as the new Black Frieza who at this stage would be 100X stronger than Leon (Jiren).