>>39073595>3No, it wouldn't.
I personally think it's bad practice to make a numbered sequel to a game if too much time has passed between installments give or take some exception (Notably because Pokémon has an on-off fanbase unlike longer running installments like Street Fighter or Mortal Kombat that can afford the gaps. Also helps that Stadium is a sidegame than a mainline title, which has also avoided numbering sequels outside Black/White). That's the whole point of a soft reboot, it allows old players to enjoy it for continuity and new players to take hold of a game for what it is.
They can take mechanics and modes from Stadium 2 and GS if they want but ultimately they'd have to name the game something else to let it stand on its own and not put pressure on the consumer to play catch-up if they missed other installments.