Both Pokemon and Sailor Moon are currently two massive titles coming from Japan. This is due to the announcement of the next generation of Pokemon games, Pokemon Sun & Moon, and Sailor Moon airing the third series of the 21st anniversary series, Sailor Moon Crystal. Fans have been inspired to mash these two long running franchise to create Pokemon Trainers using the characters of Sailor Moon and Sailor Senshi out of the female Pokemon Trainers.
Serena, the current female trainer accompanying Ash, has been turned into Sailor Moon, while Bonnie, who is also travelling with Ash along with her brother Clement, has been turned into Sailor Chibi Moon. The original female companion Misty has been turned into Sailor Mercury, the Sailor Senshi of Water. Iris has been turned into Sailor Mars, which is probably due to how dragons are associated with fire. May is Sailor Jupiter the soldier of thunder, this choice is probably down to how May did have a green outfit for Pokemon Emerald. This has left Dawn with Sailor Venus, the guardian of love.
Princess to the Silver Millenium Kingdom of the Moon, Usagi is given Pokemon associated with her kingdom. Lunatone and Clafairy are both linked strongly to the moon in both the games and anime. She is also given Delcatty to obviously reflect her having Luna as a constant companion.
Powered by water, Ami has been given mostly water Pokemon to reflect her element. She has also been given a Jumpluff which is a flying/grass type, but its design emulated bubbles which links to an attack of Sailor Mercury's.
Rei has a pair of crow that keep close to her temple, which is why Honchcrow is a perfect addition to her team. Chimecho also works for her due to Japanese temples typically having chimes hanging outside. The rest are fire types to reflect her element.
Jupiter represents both electricity and the forest, so her mixture of both electric and grass types fits her perfectly. Electabuzz also fit her tougher personality and the fact that she is helpful in a fist fight. Unlike Mercury and Mars she also has the potential to unlock a mega evolution through Ampharos.
The guardian of beauty obviously needs beautiful Pokemon, such as Beautifly. It is also clever giving her a Furfrou with a star cut paying a clear homage to her transformation sequence which uses orange stars throughout. The female Meowstic is also to represent her long-term partner Artemis.
Tuxedo Mask has a signature that he uses when he appears in battle, a rose. Giving him a Roserade is a perfect choice, while the others emulate the power and mystery behind the handsome man hiding behind the mask. He also has a shiny Magikarp which is kind of ironic, as it makes it special, but like Tuxedo Mask he is special but Sailor Moon typically has to save him as she is stronger.
Sailor Chibi Moon
The cute but needy Chibi-Usa has to have small cute Pokemon to match her. Giving her primarily fairy types plays into her personality and Skitty is clearly a homage to her partner Diana. Teddiursa has been given to her most likely due to it being small and cute, but having a moon on its forehead like how Sailor Chibi Moon does at times.
The keeper of time and space, so who better to have some dark and ghost type Pokemon. Klefki is to reflect the space/time keys Sailor Pluto wears on her waist, while Marowak is to emulate how Sailor Pluto uses a staff in battle where it uses a bone instead.
The guardian of the sky has to have flying Pokemon on her team. Honedge is to represent her legendary talisman, the Space Sword. Jolteon and Sandslash are interesting addition to her team, however in her attack "World Shaking" she strikes the earth, which would explain Sandslash.
Sailor Neptune is said to be the most beautiful of all the Sailor Senshi, so Milotic, that is said to be the most beautiful Pokemon, is a good choice. But once you make that Pokemon a shiny, it makes it all the more perfect. The rest represent her theme of the oceans and the deep.
Sailor Saturn only awakens when the world is about to end. Absol is listed to have the ability to sense coming disasters and appears before people only to warn them of impending danger. The pair were made for each other. The others all more represent her color scheme more than anything else.