Easy fix - Tanky wet noodles
It doesn't make a whole lot of sense to have tank champs like King Groot do less damage but still have the power meter go up just as fast as every other champ. If you have to hit your opponent twice as much to do the same damage, you are more than negating the slight bump in hp and block proficiency by providing your opponent with extra special attacks. To account for this, the tank wet noodles should offer reduced power gain to their opponent when striking them.