Main reason is these things
Duplication: Dupeing pokes in Gen 2 was easier than now, I want to know, are there more rare/shiny Pokémon available in these games to dupe? What game has best pokes to dupe?
What legendaries are available in each game.
Like is breeding Shinies and the shiny ditto glitch and all that available in the games?
I have been told some shinies like the odd egg aren’t in Gold and Silver and the shiny Gyarados isn’t in Crystal. (Include game exclusive shiny glitches).
Are there any game exclusive beneficial glitches?