Moku wasn’t a fan art, it was created from a “flaunt/vaunt” meme. After the Devs added “taunt” as a protect that doesn’t count as protect and “daunt” as a stun that doesn’t count as a stun people (especially Lemonsqueezy) started joking about what other “…aunt” words could be passives.
Lemon asked VKC if flaunt could be put into the game and VKC said if he does a voting thread and gets 50 votes then it will do. Official “Flaunt” petition. Please help get 50. It’s ended up with over 100 likes! So then he and VKC designed how flaunt and vaunt would work mechanically. I think Lemon told me he didn’t do the rest of the design, so VKC went and created a monster that was all about the number of monsters in each team. They made it a Moji monster because that’s the community meme monster.
There are many other monsters in the game with either a move or most of the moveset designed by people in the community. However, the monsters usually have the designer’s spin on things.
So you can either do artwork, a moveset concept or particular moves and all will have a chance to go into the game. They take inspiration from us, but you should never expect your things to be selected because only a small number are.