“I’m one of Team Galactic’s three Commanders. We’ve been trying to create a new world that’s better than this one... But people have shown little understanding about what we do. You don’t understand either, do you? It’s a little saddening... So, let’s have a battle to decide what we should do next. If I win, you leave. If you win, we, Team Galactic, will leave!”- Mars in Pokemon Diamond and Pearl.
Mars is the first of the three/four commanders in Team Galactic. She is first met at the Valley Windworks, where she attempts to take it over. She is then at Lake Verity after her plans to capture Mesprit are successful. After story mode the player meets encounters Mars at Stark Mountain. In Pokémon Platinum, Mars and Jupiter face off against the player at Stark Mountain. If you beat them, they will quit Team Galactic.
In the anime
She and Saturn both stole the Lustrous Orb in Celestic Town along with their leader Cyrus in disguise which contains the power of Palkia: a Legendary Pokemon who rules space. In "Saving the World from Ruins" she later attempted to blow up Iron Island when their mission at the Iron Ruins was a complete failure to use these ruins to pinpoint the location of Spear Pillar on Mt. Coronet because of Ash and his friends. The reason why Ash and his friend stop their mission is because of their machine thats emitting low-frequencies of soundwaves after an accident that caused all the Steel-type Pokemons to go beserk. After setting the charges, Mars and her grunts make a getaway in their heilcopter to get as far as possible before blowing it up. Mars press the detonator remote many times as she tried which completely fails because of Riley and Lucario's aura to block the explosion.
Mars later returns to Team Galactic's HQ in the end to explain all of this to Cyrus that her mission failed and ask for forgiveness, but he said her mission was just a temporarily setback. So they have to move on with the excavation of Spear Pillar which is up to Saturn that Cyrus was counting on him since the excavation was at 60%.