But for Sasaki Black Maria or WsW I don't really imagine the SH there. But with a good PU each and if they use everything they learnt during their TS why not, I can maybe accept it. (except for WsW who is the strongest F6 for me and stronger than any SH bar M4)
Well, Franky told Jinbe that FrankyShogun is modified, and he said that he will create weapons to defeat Kaido, so he must be full of cards up his sleeve, Oda can push him to Tobi Roppo level easily.
Brook and Robin I use a little bit of my imagination lol
Brook has a DF that we saw during the TS as is peculiar, he can use the dead powers of the underworld, he just needs a power-up like nightmare Luffy, only using the souls of the underworld. Oda can push him to Tobi Roppo too... Remember that Brook even hurt Big Mom's homies when he came into contact with souls.
Robin I imagine her using her powers in the same way as Netero, when he summons Guanyin, she also has her own DF power-up that Oda can turn into a massive power to defeat a tobi roppo
Don't see WW being stronger than Sasaki ... Both were said to be ex-pirate captains, and they have a rivalry. They are the strongest TR, just as Franky and Brook are the strongest outside the M4.
WW is perhaps the most promising, but Brook in FI also faced Zeo, who was more promising than Franky's opponent