Need help making one VLAN talk to other VLANs

I am currently in the process of building the network for my department's new facility.

Our current setup consists of several Cisco SG550x stacks, a watchguard m570 firewall, and another SG550x between the firewall and our ISP.

We have several VLANs setup on this network. I need to be able to pass traffic to and from one of those VLANs to several other of our VLANs. Thus far I've been unsuccessful in figuring out how to make this happen. Our senior network guy had made several references to using the ACL list to make this happen, but unfortunately he was terminated from our organization recently and now me the other tech are scrambling to figure this out.

From what I've been able to gather online I need a router device or a layer 3 switch to do this. All of our SG550xs are currently in layer 2 mode. Is it possible to do this routing in our watchguard?

Any help would be greatly helpful. Thanks.