Meioh Setsuna is the Pretty Soldier Sailor Pluto. Setsuna is quiet and mostly keeps to herself. Setsuna is very protective of Chibiusa. She is also the one in the future who Chibiusa communicates with using Luna P. Since Setsuna is the guardian of time, she knows almost everything which is going to happen. She is forbidden to tell this information, but most of the time it seems like she gives slight hints about small things.
Pluto first showed up in the R season, strictly as her senshi form, as the one who guards the Time Gate eternally. She Later she shows herself in S, as the one with the third and final Talisman, the Garnet Orb. As Pluto, she is forbidden to leave the Time Gate, but she does anyway. She also is forbidden to use her "Time Stop" attack, where time freezes in place. She used this attack once (to my knowledge) when she saved Neptune and Uranus from a helicopter explosion. That was the last time she was seen in S, and she didn't reappear until Stars.

Attacks

Pluto Planet Power, Make up: Transformation phrase
Dead Scream: Pluto's main attack of an energy globe
Time Stop: Pluto's forbidden attack where she stops time

Puto Planet Power, Make up
Dead Scream
Time Stop