Loki is injured, Gaban is recovering, same for Usopp & Brook,
Old Giant Pirates were already shown Defeated, Robin was also Captured by Sommers before,
Same goes for Nami & Jinbe against Gunko,
If Oda wanted to use everyone as Hype Tools for Imu, then why bother show them dealt with before?
I don't know what He is Planning, but I believe only Monster Trio should face him,
I Theorized long ago that in Final Saga, We would have M3 Separated from SHs similar to how They were caught at Start of Thriller Bark,
I have a feeling this Arc will End with Imu using his Portals somehow against M3 & then Off-Panels what happens afterwards, meaning We won't know the Outcome of Imu's Arrival to Elbaph until much later,