So I decided to have a look at your rules again. I'm going to have to recant my statement on synergy. Synergy sometimes takes some work to see and I'm the stay-at-home-dad of a 2yo, so my attention was maybe divided. Sorry about that, it wasn't fair. I still don't think there's a ton, but there's certainly more than I was giving you credit for.
So lets talk about your character abilities. Most of them directly affect another model exactly as it's supposed to, without really affecting the game beyond doing exactly what it says. An easy way to change this is to give passive abilities that key off of the things your models can do. For example "if this model is moved when it isn't activating, it..." This creates a synergy that your players will want to key off of. I think objectives besides killing other models will also allow you to create synergies as you choose models because they're good at scoring or moving, or make other models good at doing those things. Even like a King of the Hill thing would elevate the design, I think. And I think if you started considering those narrative keys you might be able to build a functioning mechanic around those questions, too.
Thanks for the response. I appreciate the dialogue.