There's a way the national dex situation can be solved, and god dammit, nobody's going to do it, nor does any developer have the balls! Gamefreak is focused on making the games they want to make, Genius Sonority has mostly been absorbed by GF. Nobody else has the passion or sees the potential of a pokemon game solely made for battling, like battle revolution. But how will this fix the national dex or the ever increasing number of pokemon? Simple, make a game that connects with pokemon home. You are allowed to copy pokemon data up to 3 or 5 boxes. No two of the same pokemon or same items, the only exceptions are different forms or regional variants. All the pokemon and move data are downloaded from a cloud server, as for local play, the consoles share that data. All the animations and graphics are made specifically for battling, nothing else.
The game can have various arenas and rulesets like battle revolution. Players can even make their own rulesets too that expands on battle revolution's options, such as not allowing certain pokemon, moves or items.

And the saddest thing, this game will probably never exist, even though pokemon is the biggest media franchise in the world and it's fans are known for making romhacks, fangames and other works.

Nobody will pitch it to them or make the effort, if that day ever comes, I will LITERALLY eat my shorts.