The cards were given as action replay codes from one of the blogs more than a decade ago.
Source: https://blog.naver.com/PostView.naver?blogId=superhyong&logNo=80113064521
Then I extracted the pcd files from the save file I used with the codes. The blog owner mentioned three websites:
Project Pokemon - http://projectpokemon.org/events
The Pokémon Database - http://www.pkmdb.com/
PKM 다운로드 - http://pkmdb.com/Fenzo Loves You.zip
Only the first link is working, which is THIS website, while other twos are already down.
Unfortunately, the author did not mention how he/she got the pcd file code but it is thought to be created using "Pokemon Mystery Gift Editor.exe" which is mentioned in his/her newer blog post. If the method he/she used is true, then the mystery remains how did the blog owner correctly identified the card numbers for at least 15, 16, 24, 29, 30, 31, 63, and 65. These respective card numbers from the 164.132.44.106 or 178.62.43.212, matched with ones from the blogpost.
Nevertheless still gives me the legal, legitimate Pokémon from a deliveryman.
BTW there is an oversight in PKHeX where saying Tangrowth's ability cannot have H.A. (Hidden ability Leaf Guard (2)) although the Pokémon should have that ability according to Korean community blog, who have received this gift, as suggested in the first image poster: https://blog.naver.com/PostView.naver?isHttpsRedirect=true&blogId=xaewon&logNo=55995585