I’m not sure if anyone tried to rng 10anniv pokemon, but I realize something important. Pokemon seed is generated by games save so if you use same save, you always get same pokemon (IVs, nature) and it doesn’t matter which pokemon you send. Maybe 10anniv pokemon is generated like WISHMKR jirachi or similar way. Discovering how PID generated offers us perfect IV and Nature. I'm not expert but someone can find a way.