Imu falling at Elbalf is a delusional, we already know that he isn't at 100%
The obvious plot and how it would go is like:
Luffy will fight Imu, not be enough, Hybrid Loki joins, and they perform better but still struggle
Then the wings kill the two holy knights, which we know, causes a very strong backslash on Imu, giving Luffy and Loki the chance to send him back
Somewhere along that Gunko will do something, or reveal a weakness