Yeah I mean, that should be clear. There's no way she's faster than their Genin versions.
Nah. When Sumire was serious, she pushed Mitsuki off and they went back to fighting. She's not on his level at full power, but she's definitely on his base level. Both were on their toes back and forth.
Anyway Snake Lightning is weak against Wind, Boruto has Vanishing Rasengan or even the normal Rasengan would work. Both are A --> S Rank by Manga stats. None of Mitsuki's techniques have any stated ranks to them, but I highly doubt they are above A Rank.
Boruto can pretty much break any offensive technique he has with his own, and that's not even counting the fact that base Boruto was stated to be faster than Mitsuki in the Volume Book stat. He would put Mitsuki on edge with CQC, and they can go from there. Mitsuki has no counter for his combinations or straight firepower. Boruto was able to break through the ground floor, and bust an entire foundation of a building with smashing a normal Rasengan from the middle of a room.
Mitsuki doesn't even have that kind of defense. Sage Mode is needed, then he loses.