Sprites that morph

I need to know how to replace a sprite with another sprite while the player is standing on it

Im trying to make platforms that change colour or have different collisions based on triggers. For example, a green rectangle turning into an orange circle on the trigger of a button

One problem that comes up is that when the sprite "morphs", since the circle is bigger than the rectangle, the player gets stuck in the circle if he was standing on the rectangle

Id also like to know if I can carry a variable across when the sprite changes, or how to set the new sprite to the same angle(some platforms may be rotated)

Use different animations instead of different sprites. For the overlap maybe after the morph have a loop: while player is overlapping platform -> move up 1 px.

Unfortunately my player has durations where he is upside down, and as I just found out, setting his position a few pixels up just lodges him back in an endless loop

You could move away from the centre of the platform with 'move at angle' and the angle:

angle(platform.x, platform.y, player.x, player.y)

Or move in the opposite direction to gravity.