For something like this, I'd start learning how to code again, but it's an incredibly time-consuming project, not to mention the space it would take up. Having downloaded a couple card sets(they're pretty much all available as scans, so card design isn't an issue), I know that for all the sets available, it'll probably take up at least 3 gigs of space on a microSD, if not more. Plus there's probably got to be both the full size card and a scaled down version, which will take up more space unless the program automatically scales the card down. Then there's writing the battle system. I haven't played in about 5 years because of all the extra junk they tossed in to the system for no real reason, and writing a battle script would probably be pretty extensive.
Short version: As awesome as this would be, it's not feasible until 6 or 8 GB cards become standard, and you/ your team are pretty good at coding.