But that is what it means. If her power is to make flowers bloom, then she is a flower youkai.
Not at all. Yuyuko can bring death, even when she was alive, and she wasn't/isn't a "death youkai". Flandre and Remilia have widely different powers, yet are the same kind of monster.
A character's ability does not necessarily correlate to their species, or indicates it. Remember that Akyuu describes Yuuka's abilit as being a "bonus". It's just this curious thing she can do.
Tengu and Kappa are more specific youkai types with known names.
...yes? That's exactly what I meant. Youkai can belong to a specific species, which are still classified as youkai, or not really belong to any pre-defined type, in which case they are just called "youkai" because there is no need to create a specific word for them,
because they are unique.
Yuuka is not called a "flower youkai"
anywhere. Neither in the games nor in any anxiliary material. I mean, come on, if there was such a thing as "flower youkai", there'd be an entry on PMiSS about it. Or at
least something in Yuuka's article mentioning that she's one of them, like how Letty being a yuki-onna is mentioned in her own article.
And I'm still waiting on info about that "sukima youkai" that you claimed that Yukari was. Anything man, an entry from a mythology book, a picture, a wikipedia page even, anything. I just can't find anything related to it.