Yes, Pokémon bank also works with Downloaded game. But Pokébank doesn't work with Sapphire.
Transferring Pokemon from Gen 3 to Gen 7 is pretty hard!
Step 1: Transfer a Pokémon from Sapphire to a Gen 4 game using Pal Park!
Step 2: Transfer it from a Gen 4 game to a Gen 5 game!
Step: Then Transfer it to Ultra Sun Using Poké Transfer!