UPDATE:
I used the cheapest flash card and the cheapest link cable on eBay and it worked! I think that if it works for trading, then it should work for transferring event Pokemon. All that is needed is that the "master" GameBoy (the one that says "Awaiting 2p linkup press A to confirm" when...
First of all, thank you so much @Deoxyz for making these roms available. I've been trying to find a non-hacking way to get these Pokemon for quite a long time.
I've got some questions because I want to save as much money as possible doing this. First, does any flash cart work? The cheapest one...