Transfer pokemon from gen 4-5 with flashcart

So im going about a loooong process to trade pokemon from gen 3 using my 3ds gpsp emulator, all the way to sun and moon using pksm. I can use drastic on my phone to migrate pokemon from gen 3 to 4, but i have no way of transferring 4 to 5. I have a legit white 2 cartridge, but platinum is on a flashcart. I know the legit way to transfer involves the 3ds directly reading pokemon from slot 1, so how could i go about doing this? Worst case scenario i use an emulator.