Moemon (萌えもん) is a Pokémon romhack and works related to that community. It takes the Pokémon characters and personify them into "moe" girls dressed like them.
Originally, it was a video by an individual who personified the 151 Pokémon under the theme of "Moe + Pokémon".
After that, inspired people created pixel art and replaced the original sprites with new ones.
After that, videos of the game were introduced on video sites, and the game spread rapidly, leading to the creation of a community called "Moekko Monster", Moemon for short.
Even now, new illustrations and works are being released in the Moemon community.
Tagging
Note that Pokémon anthropomorphism does not = Moemon. Furry art is not typically considered as Moemon as well.
If a third party tags an illustration that is not tagged by the contributor it's seen as very rude and annoying behavior and is not recommended.