Ruinoblade

I know this is an older thread, but it says that diamond domain waterfall should work, but I can't get up it with my seaking, which learns the move naturally (171 happiness so should pass threshold). Am I missing something?

I found answers to most questions I've had since starting online, including what the white/purple "?" means on the zone list for what pokemon are in the area. What I can't find any information on is what the circles under them mean. In some zones they're yellow (and obviously mean "available") but purple ones are sometimes with white question marks, other times a purple circle is with a purple question mark. What's the difference between these circles mean?