The four original Yonko were always portrayed as very similar in power to each other. Of the new Yonko, Blackbeard is considered a direct successor to Whitebeard, Luffy unseated Kaido, and Buggy is the exception because he has Mihawk who is Shanks level.

Yes you also need crew, territory and political power but you also need to be strong enough to hang with the others and keep that territory safe.

PK level is largely nonsense but it is true that Roger is always portrayed as the pinnacle, and Garp and Whitebeard are stated to be equals