Unfortunately, the only way to transfer Pokemon from previous generations to SM/USUM is through Pokemon Bank. This is because previous games are not compatible with the new ones. Gen 7 introduced new Pokemon, ones that didn't exist prior, so it only makes sense for the games to be incompatible. Sorry to say you'll have to use Pokemon Bank. If you want a guide on how to use it, there are numerous tutorials online that can help.
I recommend this instructional video.
For a complete guide on what Pokemon Bank is and how to use it, you can read about it in this PDF.