I think after this engagement, Imu's going to eat one God's Knight (I think it's Sommers), and a good amount of Slave Souls in order to heal up on his Soul/Sin Points.
I think a really interesting part of this fight actually connects back to the defeat of Marcus Mars in Egghead:
Gear 5 Bonney + Franky + Sanji kicking into Luffy really isn't that much straight damage. What yeets Mars here is Luffy's ridiculous ability to absorb and then redirect force. Here, in Punk Hazard, he says he can double the force: I'm willing to bet it's an increased multiplier when he's in Gear 5:
So... my question is, did Mars go back to Marijoa because of damage? Or because of distance?
Once again, Franky, Sanji, and Gear 5 Bonney is NOT anywhere near some of the strongest combo attacks we've seen in the series. I don't think Mars took a ton of damage.
I think the distance from the Magical Circles used to summon the Gorosei by Saturn is why Mars returned to Marijoa
There's no way these Magic Circles have infinite range.
I think it might be impossible to actually damage Imu enough to get him out of the country with raw damage, and that's what Gaban is pretty much trying to tell everybody.
BUT, if Shuri tells the Crew, "Hey, you don't need to kill Imu to get him out of here... if you knock him further enough away from the Magic Circle he came in through, he'll be forced back to Marijoa!" suddenly, there's a legit way out of this fight.
I think Mars showed us the key.
The secret to beating Imu here isn't hurting him, it's knocking him far away enough from the Magic Circle in Aurust Castle, so he's forced to teleport back to Castle Pangea.
So, in this case, we'd need someone to hold Imu in place (Ragnir Ice?) and then have multiple top tiers whalop Luffy until his Balloon has enough air in it to yeet Imu out of the stratosphere.
I would really like this, because it would be a legit defeat of Imu in Elbaph, without them defeating him through direct combat, keeping his aura. Gaban would be correct, they can't BEAT him, so, why not YEET him?
I will laugh so hard if Usopp turns into Sogeking and literally slingshots Imu out of the country and back to Marijoa. Oda's building up something with Usopp.