Well for the process of transferring from the 3rd Gen game to the 4th Gen there's a number of ways to do it. They way I do it like I said before is with an EZ Flash IV which ONLY plays GBA games, but since a 4th Gen Cartridge won't be able to read the game directly from the EZ Flash I have to trade from the Ez Flash to an actual 3rd Gen cart, then from the cart I can Pal Park the Pokemon to my 4th Gen cartridge. The way you stated wouldn't work because an R4 can only be played on a DS and DS's can't trade with GBA nor GBA SP's. So the only way to do it with a Flash Cart for the DS is to use DS the DeSume DS emulator which can Pal Park straight from a 3rd Gen save file, then from there load the DS Pokemon Save file onto a DS Flash Cart and trade from there to the 4th Gen cartridge you use as your main one. Either way is pretty simple. Let me know if you need me to go into further detail :P I know it may sound complicated.