To be fair I do get your stance. I did think the same as well before JN132 and the MPM Poster and OP but was always like "man they (Nebby and Larvitar) should definitely count , he may not have them in pokeballs but he literally raised them and bonded with them just like his own mons if not better at times.
After JN132 and MPM OP and Poster showed to me the writers think the same and give it the same level, I'm all that's Ash's mon Ash has had a legendary mentality now. If we give pokeballs too much credit then I guess Seaking, Stakataka and all should be given more credit than Larvitar and Nebby
I think it's so poetic the strongest Z move shown defeated the strongest mega (Steven imo was the best trainer shown in XYZ
) and the strongest G Max move
I mean that is a Z move completionist
Z move master doesn't necessarily need to mean being a completionist