There's no breeding in Legends: Z-A, so the lowest possible level is the wild encounter level. Holds a Master Ball.
Shiny Alpha Dragonite 6IV Master Ball | Pokemon Legends Z-A ZA
Shiny Alpha Rotom 6IV Master Ball | Pokemon Legends Z-A ZA Mega Dimension
Shiny Alpha Froakie 6IV Master Ball | Pokemon Legends Z-A ZA
Shiny Alpha Elektross 6IV Master Ball | Pokemon Legends Z-A ZA
Shiny Alpha Mawile 6IV Master Ball | Pokemon Legends Z-A ZA
Shiny Alpha Milotic 6IV Master Ball | Pokemon Legends Z-A ZA Mega Dimension