There's a surprising amount of thought that goes into the design of various Pokémon in the games, with different Pocket Monsters being inspired by creatures in the real world, and often influenced by mythology, Japanese or otherwise. And while newer generations of Pokémon may be more cuddly than their earlier-generation counterparts, one first-generation Pokémon, in particular, was loathed by parents, as they thought it was a member of the Yakuza.
The Pokémon in question is Mr. Mime, and while the humanoid may seem like one of the least-threatening creatures on the roster, his original design featured just four fingers on each hand. In Japan, having only four fingers is often associated with Yubitsume, which is the act of cutting off one's pinky finger as an apology, and is practiced by the Yakuza. This lead to parents drawing a link between Mr. Mime and the Yakuza and assuming that the Pokémon was, itself, a member of organized crime rings.
Of course, anyone familiar with the Pokémon will release that's ridiculous. The creature is usually treated as a goof within the anime and games. It was even in the Detective Pikachu movie, though Mr Mime was almost cut from the film. It would be rather out of character for it to be in, say, Team Rocket. Still, the link between the character and the Yakuza lead to its design quietly being changed. The extra fingers have been pointed out for some time but were mostly just discarded as "odd" until Pokémon Journalist Jon Sahagian pointed out the reason for the change earlier today on Twitter.
I noted this on PokeBeach years ago after speaking to a TPC official in Japan, but Mr. Mime gained an extra finger because parents complained about four fingers being associated with gangs. The Yakuza get their fingers cut off, so I guess parents thought Mr. Mime was a yakuza. XD https://t.co/mLwMVzigXO— PokeBeach.com (Water Pokémon Master) 💧 (@pokebeach_wpm) August 15, 2019
Mr. Mime has always seemed like somewhat of an odd fit in the Pokémon universe, but it's been in since the original entries, so it has more than earned its place. The original set of Pokémon cards, which recently sold for more than $107,000, simply wouldn't be the same without it.
That being said, there's still no telling whether or not the Pokémon will be in Pokémon Sword and Shield as the full Galar-region Pokedex has not yet been released. However, with it appearing in Detective Pikachu, it seems pretty safe to say that it's now relevant enough to appear in the next Pokémon games.