gba-link-cable-dumper VS gba-link-cable-dumper

You can also do it with a homebrew'd Wii and a GBA -> GC cable using the gba-link-cable-dumper program, or with a device like the GBxCart RW

GBA Link Cable Dumper, which allows you to backup and restore GBA saves, which you could use to inject tickets and then restore.

Link to the tool mentioned.

Hack your Wii using https://wii.guide/, then put the https://github.com/FIX94/gba-link-cable-dumper homebrew on it. Backup your Emerald save with it. Bring the save to your computer. Inject the Eon Ticket Mystery Gift using one of the innumerable ways to do it. Use the same Wii homebrew to write that save back to your cart. Have Eon Ticket.

Grab libsave from gba-link-cable-dumper and port it to the DS (it should be just a matter of editing memory addresses) and then use it to code save dumping support for gbaxxdumper. This will also support EEPROM saves, but it does mean much more effort to get everything working. Also while there's nothing stopping you from implementing save restoring, the current codebase won't make it too easy (as I was never interested in save restoring to begin with tbh, dumping is much more useful in this day and age imo)

You obviously need a way to dump saves, https://github.com/FIX94/gba-link-cable-dumper/releases is useful for dumping via a gamecube / wii using the gba connector that is used for pokemon colosseum / xd.

The homebrew that dumps saves: https://github.com/FIX94/gba-link-cable-dumper

Like I said the best you could do would be dump the save off the GBA cart and the save from the Wii/emulator, trade either with an emulator or PKHeX and reinject the save back to the GBA cart. You will need something to dump/write the save which is why I suggested a DS original/lite with a flash cart, you might be able to use a GBA GC link cable with gba-link-cable-dumper (though I'm not sure if it can write saves back to the cart), or a GC with the GBA player + homebrew. The only one I've actually used has been a DS lite with a flash cart, so I can't vouch for the other options. Another thing is if you have a GBA GC link cable you can directly inject mystery gifts and stuff with https://github.com/suloku/gba-link-cable-dumper/releases/ but the Mew will be illegal if caught in a non Japanese game

GC/Wii Mystery Event Tool, a Fork of the same tool, but injects the tickets OP listed, directly to applicable save files.

Actually adding the tickets is quite easy. https://github.com/suloku/gba-link-cable-dumper/releases can add the tickets without needing anything but the wii / gamecube and gba connector. It's a modified version of the one above. Otherwise you can use https://projectpokemon.org/home/files/file/1-pkhex/.

If anyone else needs the tickets, consider https://github.com/suloku/gba-link-cable-dumper/releases/ on a modded wii / gamecube via the link cable by doing save dumps. Perhaps we should sticky a thread of useful tools for gen3?