Yes, you can get Pokemon from Omega Ruby to Alpha Sapphire with only one DS using Pokemon Bank. If you need a tutorial on how to use Pokemon Bank, go here. It was also previously possible to use the GTS for this purpose, though it's impossible to ensure that someone else doesn't trade for your Pokemon before you get to it. The GTS currently can't be used, as severs for the 3DS-era games were closed, though it should be possible in the future if a service like Wiimmfi is created for them.
Hope this helps!