you would need an if-condition or sth similar.
e.g.:
if ....
SwitchToState
for "if" you could take almost everything, like a parameter you give the sprite, or a counter, a map flag, whatever you want.
the best example is the tut about make the sprite walking.
when you change the condition, e.g. " if MapFlag 1 is On", you could have events in your game, which turn the map flag on or off. and so you sprite could change shape, by switching to another state.