Trading starters from arceus to violet then back again issues.

I tried to look online for an answer, but didn’t get anywhere. I have three different save files right now, and I’m 4 star rank on my main play through of arceus. I decided to start the second and third accounts so that I could get the starters, transfer them to violet for the pokedex and trade them back after I evolved them.

My question is that HOME will not allow me to transfer them back. Is it because they gained levels and are now considered a gen 9 mon? I did put some high level tm’s on them but I figured that the game would automatically adjust them for what I was able to use on arceus.

Any help is appreciated!