Most of Soleil's supports are pretty bad. I really wanted to like her since that one comic I saw where she was so sweet to her father, but she's so one-note and the Ophelia support REALLY didn't sit right with me.
I don't like Xander x Charlotte, mostly because I really like Xander and hate Charlotte with a burning, fiery passion. It's a good pairing for stats, but the support is a bit overrated. Ship-wise, I prefer her will Benny or Laslow. Maybe Niles.
Xander x Beruka is bad, too. I rather like both the characters, so I was a tad disappointed. It was just weird. "HAHAHA I REFUSE TO DIE BECAUSE I MUST PROTECT NOHR" and her being hired to kill him...? It was just strange.
Ryoma x Camilla is bad. Too much Corrin worship. Same goes for Camilla x Jakob.
Elise x Niles is surprisingly sweet in the localization, but it was really creepy before. Elise x Silas doesn't sit right with me, though.
Nyx x Subaki because she rejects him...for some reason?