Whilst Oda could've made it much more obvious, I can see what he's done here. Even Luffy saw something was fishy, and he's an idiot. To everyone saying Mihawk is Buggy's subordinate, y'all are literally acting dumber than Luffy rn.
Mihawk and Crocodile are not Buggy's subordinates - that's the whole point. Mihawk neg-diffed Buggy in MF. Buggy is canonically terrified of Crocodile [
X]. Mihawk and Crocodile most likely had the dude shitting his pants when they met up; it's likely that Mihawk and Crocodile are simply using Buggy for his crew, just as Whitebeard and Marco did.
The three formed an alliance, the WG saw Buggy and assumed he was their leader. Which is funny to us, but you have to understand two things: 1) Buggy's role in the story
2) Buggy's public perception
1) All of Buggy's ambitions come true due to pure luck. He's intended to be a gag version of Luffy. One such ambition of his was to become a great pirate, which we now know means Yonkou (which he later confirmed on the way to MF).
2) The WG think Buggy is an extremely powerful individual. It's not the first time that Buggy's been seen as a greater threat to someone much stronger than him [
X]. The WG state they'll never underestimate Buggy again [
X].
Thus, they incorrectly assumed Buggy was leading this alliance and resultantly made him a Yonkou. But we the readers know the truth about these characters; from a story-writing perspective, Oda wouldn't introduce a false power as that would disrupt the actual balance of powers when this has never been the case before. After wanking the Yonkou for half the manga, would he really turn it into a gag now? In my opinion, Cross-Guild must indeed be Yonko-level but not because of Buggy. What this means is that if you give Mihawk and Crocodile a crew then you get a power that matches the Yonko, and between those two we know who the strongest is.
Oda continuously places Mihawk in Yonko-rivalling factions. First it was the Shichibukai, and no matter who else came and went they were always considered the third great power; thus, one of the long-term Shichibukai must've been largely responsible for maintaining this faction's strength - y'all think it was Hancock? And now he's involved Mihawk in Cross-Guild, making him a de-facto Yonko.
However, the problem is the mental gymnastics you've got to go through to draw this conclusion. We all know Mihawk is top-tier - he has to be otherwise Zoro would've already surpassed him. So idk why Oda won't just hype him directly - it doesn't look good for the character, especially in comparison to the way he wanks Shanks. I think he just prefers Shanks as a character, reminds me of the way he treats Kid and Law.