Flashy can't beat Kaido.
Kaido can likely react to the fastest beings of the verse (Kata, Marco, Kizaru etc) and can tank a lot lot lot : hybrid + haki, and can hit like hell.
Flashy can likely beat the F6.
Even if flashy is faster than King/Queen he will have huge problems to put them down. And both have likely COO and great recation speed. And their durability is really high.