On February 25, 2027, Pokemon Bank will shut down, leaving seven generations worth of creatures trapped on old game cartridges. It's a sad milestone if you want to keep adventuring with your childhood Pokemon pals, but if you're purely interested in completing the modern Pokedex, you still can – well, mostly. With the app's closure, a small handful of Pokemon will be unobtainable in the modern console games, and nobody's quite sure when that's going to change.
The current hub for digital Pokemon collecting is Pokemon Home, a storage app that allows you to upload your creatures from any of the Switch games. For now, it also accepts transfers from Pokemon Bank, a 3DS app which – through a long, convoluted history of transfers, trades, and Virtual Console releases – allows you to upload Pokemon from every game released prior to the Switch.