Do Solgaleo and Necrozma both have to be shiny for Dusk Mane Necrozma to have the pink and blue coloring found in the shiny dex?
Edit: Clarification: I know both Necrozma and Solgaleo cannot legitimately be obtained shiny. This is a question out of curiosity.
Only Necrozma needs to be shiny. Sogaleo and Lunala's shininess (or lack thereof) has no effect on Necrozma's coloration after fusing.