Moon

The Moon is Earth's moon, a celestial object revolving around Earth. The Transformers tend to have a lot of battles there.

Generation One
When the Autobot contingent led by Fortress Maximus arrived from Nebulos to Earth, they sought contact with the Autobots of Earth, who were aboard the Ark, led at that point by the Dinobot Grimlock. Instead of marshaling their forces, their first meeting degenerated into a duel over leadership under the Autobot Code of Combat, with the Moon picked as a neutral location. As Grimlock faced off against the injured Fortress Maximus's proxy, Blaster, the Ratbat-led Decepticons ambushed the Autobots. While the combined efforts of the Autobots allowed them to defeat their attackers, the Ark was crippled, and with the Steelhaven having left to rebuild Optimus Prime, both groups were trapped on Earth's satellite.

In a bout of extreme depression brought on by the death of Ratchet, Optimus Prime ordered the Ark landed on the Moon to allow him walk and brood alone there.

The Transformers cartoon
In an attempt to hijack Earth's airwaves and cripple the humans' ability to communicate with each other, Megatron had a base built on the Moon. After Blaster and Cosmos were captured, Blaster sent music over Megatron's transmissions to let the Autobots learn where they were. After driving off the Decepticons, Blaster commandeered the base to use it to hang.

Later, the Autobots and the Decepticons were fighting on the Moon when a mysterious voice summoned Sky Lynx, Trypticon, the Dinobots, the Predacons, the Terrorcons, and the animal-form cassettes to battle Tornadron.

Beast Wars cartoon
The destruction of the Vok's Planet Buster or the resultant quantum surge apparently gave the Moon its craters.

Cartoon
The Mini-Con ship, the Exodus, crash-landed on the Moon, scattering its stasis-locked passengers all over Earth. Later, the Decepticons would set up a base inside the derelict ship, from where they would teleport to various locations on Earth to search for the Mini-Cons.

Alexis, Carlos and Rad would later end up on the Moon when they were accidentally teleported there during a fight. Apparently, by 2010, the Moon has a breathable atmosphere but no other alterations or terraforming, as the kids are able to move about and talk, despite the fact that they should have asphyxiated within minutes.

Ten years later, the Autobots and humans had established an energon mining base on the Moon's surface, creatively named Lunar City. They assigned Cyclonus and Tidal Wave to guard it. This lasted right up until someone actually attacked it.

When he was being stalked by a mysterious invisible assassin, Optimus Prime went to the moon to lure his attacker out into the open and challenge him directly.

Kicker eventually realized that there was still energon -- and survivors -- in the ruins of Lunar City, leading to the Autobots returning there. They built a new energon tower to protect the resurgent base.

Inferno used Lunar City's repaired and upgraded defenses to blast the three artificial "comets" that Megatron sent to destroy Earth. It didn't seem to help much.

The Moon was later used as the launching point for the starship Miranda II.

Comics
The Mini-Con ship crashed on the Moon, leaving half of it and many of its occupants trapped there. Dualor took control and organised them into a community—a very well-armed community who were not allowed to leave—and declared they had to defend themselves against both Autobot and Decepticon exploitation. When Dualor abducted Earth's Mini-Cons "for their own good," both Autobot and Decepticon attentions were drawn to the Moon. This led to the Moon base's eventual destruction and evacuation.

Exosquad
Earth's Moon was the location of the fiercest battle of the entire war. In the last days of the conflict, the Moon was considered the "doorstep to Earth" being crucial to the reconquest of the central Homeworld. Having lost Mercury, Venus and Mars already, Phaeton ordered an immense fleet and army under General Typhonus' command to protect the Moon at all costs. However, these measures turned out to be in vain, when a fatally wounded member of the Able Squad, Alec DeLeon, used Typhonus' E-frame to announce that the battle was lost, thus nullifying Neosapien morale and turning the tide in favor of Exofleet. DeLeon was buried not far from the Tranquility Base, the landing site of Apollo 11.

Ben 10
The Moon is a big gray rock seen in the night with a white light shining upon the Earth. Some aliens work at this location, like Lu. In The Return, it is mentioned that Max was intended to be the first man on the Moon, but Neil Armstrong traveled to the Moon and not Max.

During Paradox, Professor Paradox travels with the team to an alternate timeline's future moon to show the gang what Earth would look like if he did not stop the time-traveling creature.

The moon is rarely visited by the team. During the episode Birds of a Feather, an Intergalactic Communications Station is revealed to be inhabited by Lu, and used a Crystal as a power source.

At the end of the videogame Ben 10 Ultimate Alien: Cosmic Destruction, Albedo in his Evil Way Big form is knocked by Way Big into space, reverting him to human upon landing on the surface of the Moon. After cursing Ben, Albedo is attacked by Lu.

Sonic Adventure 2
Eggman demonstrated the power of the Eclipse Cannon to the world by blowing up half of the Moon. The moon appears unscathed whenever it does appear in the games, such as Sonic Heroes and Shadow the Hedgehog, and it is assumed that the damage the moon took had no effect on its orbit around Earth, the tides, etc. However, in Sonic X, the moon stayed broken until Eggman re-made the other half and later, Ultimate Shenron recreated the Moon and moved the Egg Moon to Venus.

Earth II's moon
The moon of Earth II is like Earth's moon. Its significance is that it has caused some Saiyans to transform into their Great Ape form and has been destroyed two times and revived two times.

Prior to Dragon Ball
Goku is known to have transformed into a Great Ape and killed Grandpa Gohan, of which he has no recollection.

Dragon Ball
In Dragon Ball, Goku is shown to place the Monster Carrot and his men on the moon after defeating them using his Power Pole.

Pilaf's Castle
Goku transformed upon seeing the moon when trapped in Pilaf's Castle. Puar had cut his tail so that Goku would return to normal.

21st World Tournament
In the 21st World Martial Arts Tournament, Jackie Chun (Master Roshi) destroyed the moon with a MAX Power Kamehameha so that Goku would revert to his normal state after his transformation.

22nd World Tournament
Man-Wolf, a fighter in the 22nd World Martial Arts Tournament, could not turn back to a human because Roshi destroyed the moon. Master Roshi used a Hypnosis Technique on Man-Wolf to convince him that Krillin's head is the moon. The Hypnosis Technique worked and Man-Wolf turned back to a human.

Moon Revived
It was not mentioned, but the moon must have been revived during Goku's training at Kami's Lookout, as Goku in the 23rd Tournament mentions that his tail was removed so that the moon could be restored. The moon is also seen later, indicating that it has been restored.

Gohan's Metamorphosis
Gohan first transformed into a Great Ape on seeing the moon during his training with Piccolo. To prevent it, Piccolo destroyed the moon. After this, Earth II's moon was never shown again.

Moon's Image
Goku's Space pod projected the image of a moon which again made Gohan transform into a Great Ape. When Piccolo destroyed the Space pod the projector was destroyed.

Fake moon during the battle against the Saiyans
This happened when Vegeta made a Power Ball that transformed him into a Great Ape. Yajirobe cut off his tail so Vegeta could not transform anymore. Later, Gohan transformed after looking at the Power Ball. Vegeta cuts Gohan's tail with a Destructo Disk after a short struggle, but Gohan landed on him and Vegeta retreated.

Wrath of the Dragon
The moon appears in the sky in one scene of the movie Dragon Ball Z: Wrath of the Dragon. It is possible that Dende, after becoming Guardian of Earth, restored the moon when it was clear that there would no longer be threats from evil Saiyans/Great Apes.