Sailor Pluto appears in just a few TV episodes, and observations show that she really has only one true attack, "Dead Scream"; unlike the other Senshi's attack phases, "Dead Scream" is whispered rather than shouted (in the English dub it is known as "Pluto Deadly Scream", and it is yelled out like the others). Like all the Senshi of the Outer Edge of the Solar System, Sailor Pluto wields a weapon, a long key-shaped staff with a garnet jewel at its top, called her Garnet Rod, through which she focuses her power. The jewel that rests on top of the Garnet Rod (the Garnet Orb) is the third mystic talisman that forms the Holy Grail. Pluto's staff helps her control time as well as activate her attack, and is the key to the gates of time (along with the set she carries around her waist); the Garnet Rod always protects those with good hearts.
Another power that Sailor Pluto possesses is the ability to stop time, though it has been forbidden due to its potential for negative consequences. However, like the other rules set upon her position (never to leave the time gate and never use it to transport others), it was broken. While Sailor Neptune and Sailor Uranus are in the front compartment of a helicopter going to the "Mugen Gakuen" establishment, the daimons that have surrounded the school attack the helicopter, immobilizing its rotors. As the helicopter was almost about to explode, Sailor Pluto used her time stopping power to save the other passengers. While Neptune and Uranus were safely teleported onto the building, Pluto was thrown into a dimensional rift, and did not re-emerge until much later (skipping an entire season in the anime version). It is uncertain if she wound up in the rift due to the nature of the power or as a punishment for using it.
According to executive producer Janice Sonski, the final dub name chosen for Pluto, Trista, was chosen on account of the meaning of the name Setsuna. Setsuna can mean moment, but can also be a derivative of 'setsunai' meaning sadness. In the same vein, Trista, which derives from Latin's triste, also means sadness. An early dub by DiC may have rendered her name as Susanna. The packaging of Irwin dolls released in Canada in 1998 called Setsuna by the name Celia.
(from Wikipedia)