Mr. Mime is one of those Pokémon you remember seeing all the time in the Pokémon anime, but never really wanting to use yourself. This is one of those cases of Pokémon fans not wanting to use a Pokémon because of their appearance. Why?
People don't like clowns.
There's a reason you'll find quite a number of horror films with a clown as the main villain, or as antagonistic in some way. Coulrophobia is alive and well in society today and that's part of the reason why Mr. Mime is here. The fact I could find far more scary Mr. Mime artwork than I could the not so scary is telling of how the fandom feels about it.
Interestingly enough, just like many of its psychic brethren, Mr. Mime isn't too shabby in battle. It's a wall breaker, just like many of the other psychic types but it has access to moves like Healing Wish and with its speed, if worse comes to worst, it can sacrifice itself to fully heal another member on its team. Not only that but he can also set up barrier moves like Reflect and Light Screen, giving its team support. While it doesn't excel at that as much as it does at wall breaking, it's still a Pokémon with a diverse move pool that's worth giving a chance.
Image Source: Here