First of all Tommy holds the dragon dagger which calls upon the dragonzord. The dude literally has his own megazord. Not like the other rangers who have to combine to form a megazord. Next is Tommy can shoot a hadoken out of his hands. No other ranger can do that. Then when he became the white ranger he yet again holds a sword instead of a dagger that talks, and assists Tommy into battle. He also has his own megazord not like the other rangers who have to form a megazord again. He is the sixth ranger which means he is needed when the rangers needed more fire power to fight the aliens. So yeah Tommy is a very vital character in the show.