Went back and beat all of Gendo's levels! Definitely improved my skill level, I remember trying Skyfall a long time ago and just not being able to get it. Now it took a bit of time, but easily doable (just greatful you made the on/off before the first checkpoint a jump throwing the shell, not a shell jump - still not good at shell jumps)
Blue's clues and the SMB2 were the other ones I had yet to clear, fun levels, really enjoyed the boss fight on blues clues.