Whos makes quick work of this tiny man

Who's-Who, high/high-extreme diff.

Any of the Tobi Roppo could beat Vergo (probably I haven’t really seen them fight yet)

Black Maria, Page One & Sasaki would lose. Ulti, Who's-Who & X Drake would win.

Do we still count drake tho?

Technically not. I only included him since he was part of the Tobiroppo at the beginning of Wano.

Doflamingo by his own count is somewhat below Jack. Who's Who is Jack's inferior by a slight degree too. At best Who's Who is around Doflamingo's level and at worst a bit below it. Given the Beast Pirates rank people puerly off strength and no other factors and that Who's Who is not one of the top 3 but the strongest of those below it.

Even though it's weird to think about Doflamingo got power crept quickly, just like Katakuri. Luffy has to keep going to the top so he could fight the Yonko next

I'd say Doflamingo > Jack > Who's-Who

Why would Kaido send someone weaker than Doflamingo to threaten him and why would Doflamingo care about a weaker fighter than himself being sent?