so if I start over the cards I have in my mystery gift album will also be erased?
The game wipes its data when you do a restart. So, the. answer is yes, unfortunately. Wondercards are tied directly to your save file.
The only way which you can get the event again is if the event is still running to redownload the wondercard. Since Torchic and the Vivillon are over, the only event available to you is Pinsir/Heracross, if you decide to start over.
Edit: edited my post for relevancy, and to prevent confusion.
Come follow me on my egglocke! http://www.gamefaqs.com/boards/2000300-pokemon-emerald-social/69876471
Farming of event pokemon like this has been a thing for several game generations now. The tricky part has always been that you needed to get the event pokemon off of the game save before you reset it. In previous generations this required two games and two DSes. But the addition of the Pokemon Bank has made event farming possible with only a single game copy. I personally farmed around a dozen pokeball Vivillons in the recent event.