Getter G charged up and aimed with it's physical body then it moved away before the energy body made impact. NOT a suicide attack that Rocket Punch is going to be.
Oh wait, Choudenji Spin forms a drill with the hands of the mecha, sorta like Lyger. Gee a weapon part of the robot followed by the rest of the robot to provide mass/force both of which both concentrate that energy on a small area to penetrate and destroy the enemy. Nothing wrong with that it makes sense. Forcing the entire robot to change shape into a fist, that's most likely closed since it's Rocket Punch, not Rocket Chop, makes it a battering ram with it's force diffused amongst a large area instead of concentrating it while losing all of the advantages of being a giant mobile humanoid robot in the first place. If rocket punch mode is more effective then robot mode then you might as well stay in rocket punch and ignore robot mode completely. Less moving parts, less maintenance, less complex machine, more energy saving so it can probably do more rocket punch-type attacks. Oh wait, then it wouldn't be called Mazinger Z but Rocket-o Punch!!
Face it you're not going to make me like the fact that this new Mazinger is going to change into a giant Rocket Punch fist. I loved the original Mazinger, Great Mazinger and MazinKaiser. I'm not on or off the boat on this one yet. I have to see first. I'm sure my 4 and 6yr old nephews are going to love the idea of a giant robot fist though.