How are/did you guys like the new postgame sidequest with rainbow rocket? What pokemon did you guys use to face the leaders?

I have trying to use my ingame team but the box legendaries they carry are a real bitch. I imported a bunch of bros from moon but they're all level 100 and this seems like a genuinely cool challenge. I have my original team from sapphire to moon imported and I kind of want to use the team against the respective leader but I feel like that might be too autisitic.