im not sure if rua spawn normally, but during some events (like halloween part 1), both rua types will spawn as your buddy and transform after you catch them. if youre playing rn that event is over but im pretty sure u can still get "evolve 3 ghost types" as a research task that drops hisui rua

im sorry we have a record to beat

we have to find the volume of a zorua as a function of height