Hello,
Thank's for your research. Their unfortunately still missing some data especially for Mystery Gift and, because no emulator emulates infrared it's hard to test without multiple consoles ( GBC or 3DS ) with multiple versions :
You can use the "Mystery Gift" only once a day with the same trainer, and only with 5 trainer a day. The game must therefore at least record the ID of the last five trainers and some kind of timestamp for the last mystery gift.
It's technically possible to test this with only two consoles and two versions by changing the trainerID but it will take much longer.
I currently looking for this data to develop a 3DS homebrew to replace the "mystery gift" function from Pokémon Stadium but I do not have a second console to do these tests.