I'm gonna get Crystal and Odd Egg shiny hunt. If I duplicate the Odd Egg, will I continuously get the same Pokemon? I think I have heard that once you get a Egg, the game has already decided will it be shiny, what IVs will it have, etc. Is that true? Also just a side question, I think I heard that Cloning Pokemon is more risky in Crystal than Gold or Silver. Is that true?
You can clone the Odd Egg, but you will get the exact same Pokémon. If you haven't received the Egg yet, there is a variation of the cloning glitch that allows to hatch different Pokémon.
The variation should be here: https://m.youtube.com/watch?v=gZIBbWlHAWM An yes it’s more dangerous in the beginning Source
Yes it's true, the EVs, IVs, Shininess, Nature, Species, and such are all determined WHEN YOU GET the Egg. I'd suggest Saving in front of the guy that gives you the egg, talk to him to get said egg, hatch said egg, and then if it's not shiny, simply Soft Reset/turn the game off and on again.
I saw in another question that it's more risky because if you don't time turning off the power a second after the period in "Saving don't turn off the power." It will fail. So it's risky in that sense, and sometimes it can glitch and do things like, make them ???s or Lv 0(I'm assuming by duplicate you mean the cloning glitch.)I'm pretty sure they would be the same amount of riskiness though. Feel free to correct me if I'm wrong.
Source: Experience hatching eggs, and this: https://pokemondb.net/pokebase/308084/how-do-you-do-the-cloning-glitch-in-pokemon-crystal
