Im kinda sad for the mini mushroom because when in mini form you can also run on walls. Its incredibly funny to see Mini Mario just defying physics by running up and down walls.
I disagree a bit with the placement of #5. You can't otherwise kill Boos unless you have a star, so it killing an otherwise invincible enemy seems more powerful than ones with no destructive ability. Even if you had a fire flower, it would never be able to harm a Boo.
I disagree because weak powerups such the mini mushroom let mario shrink tiny run on walls an died from HIT enemy sring and boo mushrooms are both the weakest