Hashirama has shown more jutsu than anyone. He's even shown off plenty of senjutsu. What more of Tobirama is there to show, we saw his water prowess in part 1 and now we've seen his speed and FTG, nothing more to see here. His exploding technique can only be done as Edo.
We haven't seen any possible sage techniques from Minato or elemental jutsu.
Quite false actually. Hashirama has shown only Mokuton, when the man possesses Doton and suiton and can control them at will. Not to mention his freaking 10 + Scrolls.. oh please don't even get me started on other stuff..
Tobirama.. please don't even retrain tobirama to that low of a level. We have never seen his full power and his full strength.. meaning we have never seen his speed. FTG yes.. but ain't seen its uses in different situation.. Cause clearly he was about to do with the space-time barrier.. However, we don't know the scale those water techs are at now.. And we are missing his genjutsu and many other things.
You are comparing people who were well-versed in all skills of a shinobi to a specialist.
1. Sage technique are nothing more than normal techniques with Sage chakra dude.. he just used a SM rasengan..
2. Elemental jutsu that he wasn't able to equip to the Rasengan.. holy sh*t biggest speculation of Minato here.