Can you encounter legendary Pokémon during the flight to Ultra Necrozma?

Question

The part where you ride on Solgaleo/Lunala to fight Necrozma

Answer 1

in my experiance yes. I didn't know witch wormhole to go into (i just wanted to snag a few legends for the fight) and the first hole I went into I got a regirock.

Comments

See, there's your confirmation. :)

Answer 2

According to this GameFAQs thread, yes, you can.

I'm taking their word for it as I have already finished Ultra Necrozma (without the help of any legends), and cannot test it myself. I could not find any other sources which specifically specified, so I'm leaning towards this being true.