Oh Gabam say luffy defeat kaido. Kizaru realize Luffy can defeat Kaido after sensing his power like Katakuri know luffy can defeat cracker after sensing his power.
Oda wrote that statement that Luffy can defeat kaido, he doesn't mentioned it was group work but all about luffy twice in row.
Gaban trashing luddy was meant show old gaban is stronger than luffy. Post 1190 chapters luffy wlukd get stronger because he need get coc boost up like Gaban level at minimum to fight Imu.