The new boss is the EX-Z the evil robot that has escape from the machine factory.
From the poster below, I think in GAK GOD V1, there are going to have Kaiser Animals, Robot Animals and I also see Master Apollo in the poster.
There's going to be a new aura, which is the guardian spirit. Once it's full, the guardian spirit will assist in the attack.
The new boss in GAK V5
New gauge below the health which once full, the guardian spirit will assist in the attack.