I think the player should know which form comes next, so I can prepare and position myself according to the current state.
Other than that, the game is nice, I think that giving the player a more active role in the form will result in a better gameplay experience.
For instance, Wood guy is for blocking, but it's very passive and i found myself running towards the enemies to make it quicker, and you can give the player the ability to shoot the fireballs in the other shooting form etc.
Good job!