So I've been trying to get Porygon ever since I saw its shiny. Since I am currently doing a shiny-only run, I thought it could be a good addition to the team. I recently completed the quest for it and was ready to soft reset or run away until I find it. However, Rejuv suddenly becomes nice to me and gives me a shiny first encounter. I was pretty hyped but then realized, "could this be guaranteed?" I've searched it up but couldn't find it.