I do the same. I prefer ability synergie over mono. And I'm not convinced mono is better, even with personnal equipment. It's only +10% ATK +10% DEF. While in ability team it's thinks like x2 skill rate or +too much% Crittical rate/damage. Or full counter. Or other things.
The best thing is still mono and ability if you can but for me mono is a bit less important due to smaller boost. Even if actually I try to do teams with 3 girls of one color and two of other colors if I can.

ceekay> Hi. If you and your husband (playing both FkG is cute ) search for alies, I have a ton of free slots. I'm not that much strong but I can at least go through any event stages easily. All informations are in my signbut helped squad and total power are old.