MovesetBot hasn't always existed. Pokemaster devised it in late 2013, and the first moveset questions were posted in 2010. That means that everything until Gen 6 was posted by a real user of PokeBase. (Black and White were released in Japan in 2010, so we had the full Pokedex available, just without English names.)
In 2010, PokeBase was much smaller, and the moveset questions functioned more as a discussion between a few active users at the time. They weren't strictly moderated nor as "official" as they are now. We did a fair amount of work to make the oldest ones fit the modern purpose they've found themselves with.
For context, you can think of MovesetBot as Pokemaster on an alt (sorry to ruin the mystique of it). My understanding is that he doesn't do anything manually with the account, and simply uses a script to "inject" the moveset questions into PokeBase's database.