do you have a slot 2 card?

 

There will be no help for you until you clear up what is going on. You left everything very unclear.

-Firstly, what are you loading the GBA ROM onto? Supercard SD? EZflash 3in1? You need a slot-2 flashcart, it doesn't just link up your GBA save on the slot-1 microSD. You need to have Supercard slot-2, an eWin, or an EZflash 3in1. Do you have any of those?

-Second, if you have a slot-2. You need to patch your Pokemon Pearl for SRAM reads. Slot-2 flashcarts save differently than original Pokemon GBA game carts, and your Pokemon Diamond/Pearl will need to be patched to recognize that save. NOTE: If you are using an ORIGINAL GBA Pokemon game you must not patch your Pearl like that. If you do it will be start working the other way around and read pokemon off flashcarts but not off original games.

-Thirdly, YES you WILL have to use Pal Park after you meet the conditions above. It's 6 pokemon per day, no workarounds, just like on the real thing.

 

I think if you're using both a Supercard DS and a slot-2 Supercard, you don't do any patching of either game, other than selecting the appropriate settings in the on-board patching menu. Obviously if you're using a 3in1 you'll need to patch the Pearl rom, but if you're using the Supercard's built-in linkup ability, I'm pretty sure it's imperative that you don't patch anything.