Worth pointing out that most of the "Megaglitch"'s effects are actually just a result of an older version of Gens not knowing what to do. Act 1.5 is a legit glitch though, and Blue Knuckles still appears in the level select if you trigger the "Megaglitch" regardless of what official version of the game you use.

Put together and uploaded because I know someone out there's gonna find it useful. I'm not sure what the exact trigger is - when I did it by accident, it was because I broke a ramp sequence, but looking it up on Youtube showed different methods. Plus, the glitch draws the cycling palette data from Act 1 for the rock "undershine", the general Act 2 palette for the stage and the 'cavern' spaces, the Boss Sub-Act (this one was a bizarre find) palette for the pipes, and a purple color not used in any of the aforementioned stage entries. I relied on Youtube to fill in the palette blanks in a similar manner to how I acquired the Super Knuckles palette in Sonic 2 2013's Hidden Palace Zone.