First off, Orochimaru can easily locate Mū whilst the latter is invisible through
You must be registered for see links
[
You must be registered for see links
][
You must be registered for see links
] by
You must be registered for see links
from his body via his Snake Binding Hand variants or just releasing a snake from his mouth. I think we can reasonably assume that Mū's invisibility technique doesn't mask his body heat. Given the fact that these snakes can be summoned on a whim, invisible sword slashes and sneak fission tactics aren't happening. I assume that Mū will make himself invisible at the start of the battle which is why I'm pointing this out first. Spores can be released into the air to protect against this as well. Remember that these spores can't be sensed beforehand by conventional chakra sensing since most of the Gokage and their body guards were tagged despite skilled sensors like
You must be registered for see links
,
You must be registered for see links
,
You must be registered for see links
and
You must be registered for see links
being present when they were released. And yes,
You must be registered for see links
before anybody argues otherwise, yet the spores weren't picked up anyway.
Orochimaru can summon some
You must be registered for see links
or have some relatively smaller snakes
You must be registered for see links
as distractions to buy enough time to replace himself with a shadow clone, and hide underground to keep himself safe and continue to track Mū's movements. Keep in mind that Mayfly is undetectable by sensors. Black Zetsu was able to snoop around across different battlefields right under the nose of the SA's sensory division. Now Mū has to account for two separate entities which he can't distinguish and one that he probably can't even sense as well as some snake summons and possibly Manda himself. Immobilizing these summons isn't going to be an easy feat since they can track Mū through heat sensing as well, he needs to go visible to use chakra, and he can't simultaneously make the snakes too heavy to move and counter Orochimaru and/or his clone's attacks.
Jinton from long range is evaded with Oro's clone having knowledge of Mū's relative position at all times. Even if he vaporizes the summons, the real Orochimaru is safe underground and has the reserves to engage in a prolonged fight. While sick and inside of a host body that was rejecting him, he used Oral Rebirth thrice, used Sanjū Rashōmon, and used Formation of 10,000 snakes which is one of his largest AoE snake techniques. Summoning just one gate takes a a great amount of chakra as noted in the
You must be registered for see links
, and he summoned three of them while using other chakra taxing techniques. Furthermore, his reserves are significantly boosted by the Senju DNA. This of course means that he can summon more snakes in case Mū manages to immobilize/vaporize them which takes less chakra than using a Kekkei Tōta.
Mid to short range - Orochimaru's clone can counter and disrupt jinton's prep by
You must be registered for see links
or
You must be registered for see links
and the snake carrying the blade (maybe even go into slithering snake mode as well, if possible) to push the overall speed and momentum of the attack [same counter can be used if Mū tries to go for jinton from the beginning]. The real Oro hiding underground, who remains undetected through the use of Mayfly, can come from underground and nail Mū with Kusanagi, a paralysis juinjutsu, or the five pronged seal depending on which move is the most viable. An attack from a boss summon can also be incorporated if Mū hasn't disposed of them yet. If he misses, then he can reset and hide underground. More than one clone can be utilised to increase the success rate of this strategy.
It could probably go either way but I think Oro can take Mū with high difficulty.
