>unique visual style completely unlike all other Pokemon
>varied but unified in appearance and theme
>break the usual "Legendary Trio" mold
>atmosphere and lore builds them up as powerful and mysterious monsters
>connected deeply to game's story and lore without being overly shoved down your throat (except for Tapu Koko, maybe)
>very good in competitive, and all have unique niches
>half of them are waifus
The Tapus are genuinely some of the best designed and executed Legendaries in quite some time. It's no surprise that they're so popular.
