That part in CV3 where you have to wait for falling blocks to "build" your way up is fucking horseshit. I always opt to bring Alucard there for bat skips because like that vanishing block segment of Heat Man's stage, I just can't be bothered after I've done it legitimately once. I would prefer any enemy filled hall to that endless purgatory.
Also, Adventure Rebirth Stage 3 on Hard mode. I know I've beaten it on Hard but going back recently, I honestly can't imagine how.