Luna
Luna is Sailor Moon's guardian cat. She is their to train
Serena/Sailor Moon and the other scouts. She is also the one who gave the
scouts their transformation pens and Serena her locket. Luna is the blue
cat.
Artemis
Artemis is Sailor Venus' guide cat. When she was in England
he trained he to be Sailor V (who, by the way, is not the same as Sailor
Venus). When the scouts were finally reunited he helped Luna with the training.
He was also central control. Artemis is the white cat.
Diana
Diana is Reenie's guide cat in the future. She is also Luna & Artemis' child in the future. This causes some confusion however, Luna thinks that Atremis is sleeping arround. (But of course, this is not true. But when they find out the truth everyone is blown away.)