Thank you so much for the answer! We do not know how to use Pkhex, so I write pokémon here with all the information I can give:
The game is Pokémon Y (Italian)
Ho-Oh: (Any non-shiny Oh-ho in-game will be fine!)
Victini:(event with V-Create) https://projectpokemon.org/home/search/?&q=Victini&type=downloads_file&nodes=2,4,5,8,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,56,57,88,90,127,128&search_and_or=or&search_in=titles&sortby=relevancy
Mesprit (Any non-shiny Mesprit in-game will be fine!) https://projectpokemon.org/home/search/?q=Mesprit&type=downloads_file&nodes=102,111,118,127,128,129,136,137,138,140,141,142&sortby=relevancy&search_and_or=or&search_in=titles
Like other moves are good those present in the file (the children will change if they want, through levels or using the heart scales).
Only request: not shiny! Children like the original colors!
Thank you so much and I hope you can help us!
PS: If possible, a Charizardite X and a Mewtwoite X