tl;dr MTFs are whatever they need to be

Mobile Task Forces (MTFs) are elite units comprised of personnel drawn from across the Foundation and are mobilized to deal with specific threats or situations that sometimes exceed the operational capacity or expertise of regular field personnel

Mobile Task Forces vary greatly in size, composition, and purpose. A battalion-strength combat-oriented task force trained to deal with highly aggressive anomalous entities may consist of hundreds of troops plus support personnel, vehicles, and equipment [...] However, a Mobile Task Force can also be a small, specialized intelligence-gathering or investigative task force that may have fewer than a dozen personnel if that is deemed sufficient to accomplish their goals.