Has Sonyas primary P2 colour changed since the patch? Seems alot more green with a white tshirt...? Was it always like this?

For me the coolest alternate color is Sub-Zero revenant white ice color, looks awesome and make the unbreakable mask look like it fits with the rest of his attire.

Yea Subs rev with the p2 is really good, I like Shinnoks alt with p2 colors too.

I've been using P2 colors exclusively with Mileena and with Jacqui's standard outfit and it improves all the costumes by leaps and bounds. (Boot Camp Jacqui I prefer in P1 colors.) Kahnum Mileena P2 is a lovely royal purple color instead of pink. Very regal.

Is there a way to choose the alternate colors without it being a mirror match?

Go to the 'select costume' option, and on PS4 you push 'option' instead of X... I imagine it's the same for Xbox but with start or whatever.

Ermac's Primary
Raiden's Primary
Kitana's Dark Empress
Mileena's Tournament
Scorpion's Tournament
Sub-Zero's Revenant

These are like my favorite for P2 colors right now.