First you need a hacked switch to extract and inject saves on the switch.
If you dont want/dont have a modded switch , use a bot to send the pokemons to your game.
Next, if you want to use pokemon online with a modded switch, you must have a legal copy of the game.
If you have that, then pkhex its the easiest part
You can:
A) download a save and inject it on your profile
B) download a save, extract the pokemons as pkX files and inject them to your save
C) create the pokemon manually and inject it to your save
D) donload the pk files and inject them to y
Maybe if you exclude some pre evolutions or evolutions its doable, i mean most have for example
Bulbasaur, ivysaur and venasaur
But if u keep only 1, the boxes might be enough
Alguien me habia comentando que igual no le aparecian con los archivos, en mi caso lo consegui cambiando uno de los regis x home, te recomiendo intentarlo, por que creo que el juego no lo reconoce si solo lo injectas
I made some pokemons on pkhex, it marked them as legal, but i havent tested yet, if anyone want to test them, plz let me know
there are many legendarys from older versions (rayquaza, solgaleo, lunala, etc) shiny
crown pk.rar