JaxKasatushi

Hi! I'm new to the Forum, so apologies if this is in the wrong place. I'm trying to give myself the event Pokemon such as Marshadow/Zeraora but the trainer information is being autofilled, so when I save the file and load my switch they don't obey me. If I go back to the save and update my trainer information, it then deems the Pokemon as illegal. Is there another way to legalise Pokemon from past events to still legally get them and they obey me? Thank you in advance for any help!!