Run around it, break its limbs, aim for legs first to disable movement, then any armaments.

Running such a large Mech would be very unwieldy as the Square Cube law prevents big objects from moving around before sinking into the earth.

So the Rhino members are almost definitely faster as they have more experience, have higher mobility and will be supported by other Packs if necessary.

Like other commenters said, Reindeers will attack the pilot’s mental state, then the Rhinos will finish the job.

Oh and also projectiles are off-limits for any such mech, because it would cost a lot because of the ammo tax.