Shiki showed one of the craziest feats in the movie when he was freely moving islands massively dwarfing Dressrosa and Onigashima in size. I know Pre TS Luffy beat him but Shiki was also casually cutting two mountains with his legs as if he was Madara. Again, very casual.
This mf challenged Prime Garp and Sengoku to a 1vs2 fight and managed to destroy half of MF. Shiki ain't no slack.