So, as you can see, I have an answer here that needs updating and reformatting:
https://pokemondb.net/pokebase/362428/what-are-all-the-pokemon-that-have-appeared-as-a-shiny-in-tcg
It was going to be the English set name and then the Japanese set name (because it is clearly mandatory to include Japanese set names (why do I do this to myself)), followed by the cards in that set. For example, something similar to this:
"EX Holon Phantoms (Holon Phantom)
Gyarados ☆ δ, Mewtwo ☆, Pikachu ☆"
...Which was all well and good until I learned that Mewtwo and Pikachu aren't in the Japanese set. They're apparently found in a deck kit. So what do I do? Add the Japanese set/whatever name next to the Pokemon instead? Throw in a note? Or something else?