The fight before the Greed Mode final boss is various Greeds instead of Monstro now, which means you can get extra money when you kill them to donate to the Greed machine, that pretty much solidifies what I assumed about Ed's cryptic tweets
Also there's a percentage on the HUD when you get to that point that tells you the chance that the Greed machine will jam on that character, encouraging you not to just playing the same character over and over