Oooh, this would be such a cool mashup!
I have a feeling that Hollyleaf and Glory would get along well, but I'm not sure. They're both good leaders and strategists.
Moonwatcher gives me major Dovewing vibes, so I can definitely see those two hitting it off. They both know what it's like to love someone they're meant to hate (ShadowClan/ThunderClan, Nightwings/Icewings).
Also, Turtle and Jayfeather are stick bois
TM. However I don't think they would get along, since Jayfeather has such a snarky attitude and Turtle is a bit more on the sensitive side.
Pre-Book-Seven Winter is very similar to Breezepelt, but they both seem to hate everyone so I think they would just clash with each other. Tbh Winter would probably kill Breezepelt rather than put up with him xD
Tigerstar I and Darkstalker would immediately hit it off. They both hate their fathers, want to be leader/in control, and are extremely charming when they want to be. I can just imagine them plotting together
Generally, I think certain tribes and Clans would get along well. Like, I can see RiverClan cats being fascinated by the SeaWings and their diving skills, glow-in-the-dark stripes, etc. ShadowClan cats would probably feel the same way about NightWings (but only the ancient NightWing tribe, when they were still considered mysterious and dark).