However, from my understanding, a lot of (but not all) of the eShop levels were already technically in the game's memory, and a card needed to be scanned in order to access that content.
Well in the case of the original SMA4 game, the extra content was already in the ROM, you just needed to unlock it.To both, this is incorrect.
All of the level data is stored on the e-card itself. The cards actually hold 1.2K and 2.2K of data on the short and long strips.
I haven't looked at Nintendo's virtual console ROM, but I believe it took all released extra levels (which was more than the 32 the e-reader could even hold), hacked them into the ROM, and made them all accessible. I think ShadowOne333's 'hack' just turns the GBA ROM into the virtual console ROM and doesn't actually add/do anything that Nintendo didn't already! He extracted the virtual console ROM and made a patch of the difference between it and the GBA ROM probably. It's basically distributing a Nintendo made hack. If this is correct, it should definitely not be here.
Perhaps ShadowOne333 would like to chime in.
Personally I think a patch should not include any data not made by its author.
To merge data from multiple games, the patch should require memory dumps of all the games as the input/target file of the patch, not just one of them. This way these patches could be shared without an issue.
Agreed. ROMs shouldn't be allowed, even if you hide them in your patch! You can easily accomplish the same thing without issue. Although you can surely find some copyrighted data in our regular archives, it's usually due to technicality such as shifted data and/or limitations of IPS (difficult to police). It's usually not intentional. Anything that is intentional really shouldn't be here and I think that would be in violation (and likely also removed if flagged).