FYI I would think of the "one hit wonder" category as being fairly lenient. If there was a random song that you barely remember from a band but it at least charted for a week or two, that doesn't IMHO exclude a band from being a one hit wonder.
For example A-ha might have had other songs that charted, but I just googled them and from a list of songs, I can't remember a single one of them based on the song title. Maybe that's just based on the fact that when "Take On Me" came out, I was about 7 years old. But looking at their Wiki page, only one other song (from the same album) ever reached top 40 in the US, and then nothing from their subsequent studio albums charted.
So I'd call A-ha a one hit wonder.