I guess we are going to have to agree to disagree on the subject regarding the possibility of a Mega Z Pikachu.
I can think of no reasoning to why it would be unlikely to consider a Mega Z evolution for Pikachu, the mascot of the franchise, and especially Ash's pikachu.
To our knowledge , as audiences, there have been no content presented by gamefreak hinting that mega z evolution is exclusive for pokemon that have one Mega Evolution.
The franchise has often given Pikachu exclusive battle gimmick power-ups, and I see no reasoning for why mega evolution would be excluded.
Its obvious the pokemon franchise favors Pikachu more than Raichu, especially Ash's Pikachu. Having Ash return and reveal a surprise exclusive mega evolution z gimmick for Pikachu would be very germane to his story, since his pokemon have often gotten exclusive power-up forms; Aura Mega Lucario, Ash-greninja and 10 milllion volt Pikachu to speak examples.
There is literally a reason called Mega Raichu Y.
No matter you try to argue it, it doesn’t make any sense to give Raichu a 2nd Mega Evolution that heavily resembles Pikachu to the point that it basically is a Mega Pikachu in all but name and mon it Mega Evolves from if they had plans to introduce an actual Mega Pikachu.
Also if Pikachu were to get a Mega Evolution it wouldn’t be called Mega Pikachu Z it would just be called Mega Pikachu, because Z-Mega Evolutions are for Pokemon that already have a Mega Evolution.
Also in regards to the argument that “
To our knowledge , as audiences, there have been no content presented by gamefreak hinting that mega z evolution is exclusive for pokemon that have one Mega Evolution.” Yes there is something that hints at Mega Z Evolution is only for Pokémon that have that have one Mega Evolution and that is the simple fact that all the current Z Mega Evolutions have been for Pokémon that already had a single Mega Evolution.
Right now there is nothing that indicates or hints that they will give Pokémon that don’t have Mega Evolutions or already have two Mega Evolutions Mega Z Evolutions.
You seem to be misunderstanding something the burden of proof isn’t on proving that Mega Z Evolutions are only for mons with a single Mega Evolution, as the burden of proof is on the idea that it isn’t exclusive only to Pokemon with a single Mega Evolution as there is literally nothing that even remotely suggests, hints or supports this.
Also in all honesty there more likely to have Pikachu stick with unique signature Z-move and then just have Ash come back with a Mega Garchomp Z, Mega Absol Z, or Mega Lucario Z rather then going out of their way to give Pikachu a Z-Mega Evolution when it doesn’t even have a standard Mega Evolution.
Plus let’s be realistic here if they had plans to introduce a Mega Pikachu then they could have easily just called Mega Raichu X Mega Raichu and called Mega Raichu Y Mega Pikachu and make it Mega Evolve from Pikachu.
It extremely unlikely that if mascot of the entries franchise was getting a Mega Evolution that it wouldn’t be one of the Mascots for the Mega Dimension DLC.
No matter how you try to argue this Mega Raichu Y being made to heavily look like Pikachu to the point that the resemblance to Pikachu is specifically pointed out is basically there way of telling you no plans to give Pikachu a Mega Evolution.
There also no need for Ash’s Pikachu to use Mega Evolution when it can just stick to its signature Z-move.
Also in regards to the argument that the franchise obliviously favors Pikachu over Raichu is hilarious when you break down the battle gimmicks they have with Raichu coming out on top which breaks down like this:
Main Battle Gimmicks Pikachu has:
2 Signature Z-moves
Gigantamax Form
Main Battle Gimmicks Raichu has:
Regional Variant with said Regional Variant having a Signature Z-Move
Two Mega Evolutions
I mean heck when push came to shove they specifically decided to give Raichu two Mega Evolutions and make one that heavily resembles Pikachu to the point that it basically looks like a Mega Pikachu over giving Pikachu a single Mega Evolution is really telling.