Use SpringBall to bounce on the crumble blocks, then unmorph and shoot the door open.

Requires:

"canPrepareForNextRoom"
{
  "or": [
    "SpaceJump",
    "canWalljump",
    "canCarefulJump",
    "canStationarySpinJump",
    "canCrumbleJump",
    "h_canUseSpringBall"
  ]
}

Unlocks doors:

{"types":["super"],"requires":[]}
{"types":["missiles"],"requires":["never"]}
{"types":["powerbomb"],"requires":["h_canUseSpringBall"]}