I love Alexis-Erynn, simply because they are best friends, their personal connection being so strong is what pushes it up to God tier.
Erynn-Melissa is another one i can't help but be curious.
Alexis-Iris and Erynn-Iris i also don't know.
Alexis-Layla and Nikki-Cara have nothing (well... Alexis-Layla has one scene

) without the secret paths... the SPs haven't had much love from Nyx until now.
Still i'll make a double SP, evil older sisters once the new version comes
Layla-Gabi, is another strong one... Gabi is a must for Layla playthroughs.
Everyone else doesn't have much play with Layla, Alexis has limited actions with ASP, Erynn-Layla is getting taken out, Elena path is sad and not rivalry... and Val won't cross her.
For Nikki... she already has a bit of rivalry with both Val and Erynn, 2 good combos for her... she hasn't met anyone else.
For Val since Nyx already pushed it as one or the other... i wanna see the consequences of the Alexis combo... multiple paths, Alexis dumped, lie to both... and maybe the "second chance" option?
Cara... Yeah she's gonna get backstabbed by Nikki in the SP, she has met Erynn and Melissa but they don't even consider her a rival.