This achievement requires beating Vena after having obtained air dash but not high jump, double jump or slide. Freeroam mode adds in the rabi-ribi hidden tech such as reverse walljumps and wall kicks, so clearing the game at least once to unlock freeroam mode is required for this achievement. The only item required to reach airdash with this route is the bomb from the first area. Difficulty doesn't matter, so Cakewalk is fine.
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