I notice a lot of Pokemon I've got have that, but not certain event Pokemon supposedly from Japan. Are they legit or hacked?
Pokémon from a Japanese game will always have the JPN mark in the PC. Your others might be hacked because when the hackers make Pokémon with their programs the default language is usually English and they forget to change it.
I don’t know that I’m right for certain but I'm pretty sure I’m correct. If you have any, further issues then feel free to leave a comment.