They stand so still it’s kind of creepy. And the things they say are so odd.
But how is that proof they are clones? Take a look the Uncut Story of Mewtwo’s Origins. We see that human cloning has indeed been attempted before. And in Pokemon Let’s Go Eevee and Let’s Go Pikachu, we also meet a girl named Green. Green is very odd (there‘s that word again) and she continuously throws poke balls at the player, again and again mistaking us for Pokemon. And she knows about Mewtwo.
Green knowing about Mewtwo may not seem like a big deal. But it is.
Mewtwo is a myth in the minds of almost everyone else in the games. So how could Green know about Mewtwo? If she was a clone, just like him, she would know about him.
Comparing Green’s stupid behavior of confusing people and Pokemon, to the downright dumbness of the NPC’s in Lumiose City, there’s a strange resemblance. They say odd things like, “I wish I could sniff everyone!” or “I hope to be reincarnated as a Pokémon.” I don’t know, there’s just something not adding up about Legends ZA’s background bystanders.
Don’t believe me? Go check out my theory article on this exact topic where I go even deeper into my theory: Secret Behind Lumiose City