I decided to start the Fifth Party with a large group shot of pretty much every character that's appeared in the comic up to that point. Starting on the left, we've got Shadow Man, Treble, Rush, Chadling (in Demon form), Alternate George (missing eyes), Alternate Beat, Tango, Auto, the Shadowy Author, Alternate Bass, Napalm Man (who's currently hanging out with Alternate Mega Man and Bass), Alternate Mega Man, Mike, Mega Man, the Author, George, Proto Man, Roll, Techno, Eddie, Dr. Light, Ran, Kalinka, Dr. Cossack, Bass, Dr. Wily, Nate (in Demon form), Zero, X, and Liss. I think the only character that's not there is Bob.
In the second frame, where the Author is talking to Shadow Man, you can see cameos from Rick, Plague, and Myrmadon. Also, the Author's dialogue is referencing playing Monopoly with an Eskimo.
In the last frame, where Alternate Bob is introduced, I was a little concerned that the purple scarf wouldn't be visible enough to clearly identify him, but I figured if his portal was somehow rainbow colored as well, it should be pretty obvious.