Ok
First. Samehada can't find him when he erases his chakra existence.
Second. Muu is skilled in double swords so it would be a fun sword fight
3rd. He has wind, earth and fire release. Wind being electric weakness.
Its a pretty tough battle for Muu. As Muu has devastating techniques with dust. But Bee in 8-tails form is pretty tough and would overwhelm Muu.
Only counter to his 8 tails Form would be either
1. Fly high in the air and Spam dust release and hopefully it should damage such a huge target. Like when Oonoki was about to dust release on the turtle island. I assume that it would do massive damage to the Hachibi
Or
2. The move Oonoki did to Muu which made his weight to the point where he couldn't move, would be something he could pull off on the Hachibi
It's a toss up.
Btw Muu is far more analytical then Bee. He was fighting 2 kages and Naruto 3v1 don't base it off that fight, he was putting up a fight against those 2.