I need help with the horrific "this version is not compatiable" on Pokebank!

I am trying to hack into my Pokebank account on my old SD card instead of going around trading Pokemon with people online. Is there a way to hax my account in order to get back my legitimate event mythical Pokemon? If so, how should I do that? I made the mistake into buying a digital copy off Amazon, which came with the code. Then put down the code on Pokebank, and my old SD card could not manage that much data, but started the game anyways for the reason of keeping my PokeTransporter and Pokebank instead of deleting them. So I went to buy an SDHC card. This gets even more terrifying! I got it, put it in, and started the game after setting all of my mythical events from Sun to Ultra Sun except Marshadow. Then I started the game again and I was shocked it started a new game. Progressed through the game angry, and saw my Boxes. All completely empty. The same with Pokebank. Then I put my Old SD card in and it said "Data not compatiable with this version".