Sailor Pluto is the lonely guardian of time and rarely interacts with the rest of the Sailor Senshi. She is good friends with Chibimoon in the future and spends most of her time with Uranus and Neptune.
Sailor Pluto has the Time Stop ability which comes in handy in every battle you could possibly imagine. You can use it, restore all of her EP, and then use it again while all of the other Senshi use their strengths to win the battle.
Not a single one of her statistics is that high, so she is going to need to be healed often. Be sure to put her into the back row to be sure she doesn't get easily defeated.