Given how we were shown he has some sort of weakness to being outside of MJ, Id say none.
The weakness is the presence of Zori, the one Imu himself indirectly called the pinnacle of existence.

Other than that, we really dont need Imu in WG war, that can be fought between Elders and Revolutionaries. The only issue is if Imu dies, everyone in contract with him might die as well, at least those who were kept alive past their normal expiration date...
Here in Elbaf, we have War God, Sun God, Demon God and whatever Imu is, perfect opportunity to drop major stuff here.
In WG war, someone will backstab Imu anyway, whether Garling/Shamrock betray him or he ends up Blackbeard's victim, the fact that he doesnt have to share spotlight with anyone in Elbaf is perfect and a great plot twist to take him out here and now.
But yeah, Oda is probably too pussey to make a move like that.