I mean, Arararararagi should be fine in Gensokyo, for most part.
usually tries to talk it out, rarely actually fights. if he does, the results are mostly "he loses" or "the opponent is spared" Seishirou is an exception, since he came back from dead; so they basically exorcised him
plus the darkness kinda does the "if youkai lose their belief they die" (though in this case it's more "if oddity changes its behaviour enough it will be deleted").
oh yeah also there's the vampire who came from the West in the distant past and if left unchecked could bring bad times
