Tip: If you make a change to your ROM that you regret, just go to File > Restore > Restore ROM to Previous State in the menu. From there, you can select a restore point and revert your ROM to a previous state.
Blocks, which sets Mario's power up state directly but as opposide to the cheap ones which can be practically made by everyone (even by a tool), these also include an animation to play for each state like you would have gotten the corresponding powerup or, in case with become_big.asm, a different animation for each powerup state à la my powerdown patch.
In additon, these disable flying with the cape to prevent glitches.
Absolutely no credits required.
note: become_big.asm works natively with more power ups but requires some edits to add powerdown animation for each power up.
Nice set of blocks, and slightly better than Boingboingsplat's version since it didn't include a power up removal and I kinda like your become_big block more with the different animations depending on the power-up state.