pkhex supports gen 1 - 7. Issue is exporting say gen 7 pokemon to gen 1 chucks an error the pokemon not right format/missing info. Could always just recreate a pokemon using it anyway.
If they stuck with original 151 the game would get stale eventually they would need to add more putting in same position. If they made a true open world mmorpg that would be suicidal for profits no one would need to buy any newer games and will just stick to that. (same reason pokemon go didnt...
Worked for me but had to do some stuff as it said not supported at first. Had a few issues with contact had to clean them all off. Wasn't sure what HW version it was also so had to put AKAIO back on an SD card boot it up and press start go to more then help and it showed it was HW81 :D...