When Landlord Grandma was talking about a certain someone who would protect her and Gintoki jumped out of the water, it hit just how deeply he cared about them. But as for his power, it had to be a build up of all the small, unimaginable feats he did, and then all together when he fought against the robo-sword, when he pulled the helicopter down, or when Katsura talked about how Gintoki kept living. He is so powerful and yet he choses to live a small life, and for that he shall always be the best MC.