Tiled only ships with a few small example tilesets, so generally you're expected to bring your own tiles or find them online (like here on itch.io, or on opengameart.org). I'm sure you can find Pokemon tiles or something similar. :-)
I really appreciate your interest in supporting me, but when in doubt whether Tiled suits your needs, just download it for free! If you want to support further development you can always come back here later, or donate through other platforms.