Mihawk was extremely well represented in tournaments. To compete in the format, other decks needed an answer for him. The meta therefore revolved around Mihawk, his counters, and sometimes even the decks that could beat those counters.
His departure will necessarily change the balance of the format. Some decks lose their main bad matchup, while others instead lose one of the matchups that justified their place in the meta.
The Biggest Winners: Xebec and Elbaf Luffy
Rocks D. Xebec
Rocks D. Xebec is the biggest winner from this Ban List.
Mihawk was his biggest counter. Outside of that matchup, Xebec mainly has a negative matchup against Elbaf Luffy, but performs very well against the rest of the current meta.
However, it is important to consider that decks have so far been primarily built to face Mihawk, not necessarily Xebec. If a large portion of Mihawk's representation shifts to Xebec, deck lists will logically start to evolve to face him more effectively.
Xebec should therefore be extremely common at the start of the new format, but it remains to be seen how the meta adapts afterward.
Want to explore the decklist and game plan? Read the Rocks D. Xebec OP17 Deck Guide.
Elbaf Luffy
Elbaf Luffy also benefits greatly from Mihawk's departure, as Mihawk was one of his very bad matchups.
However, it still has other difficult matchups, especially Sabo and Luffy/Ace.
Its main advantage in the future meta is its matchup against Xebec. If Xebec becomes as common as expected, Elbaf Luffy will have an important reason to remain at the top of the format.
Xebec and Elbaf Luffy are therefore the two decks that benefit most directly from Mihawk's ban.
Want to explore the decklist and game plan? Read the Monkey D. Luffy OP17 Deck Guide.
Decks That Should Remain Competitive
Sabo OP13
Sabo does not benefit from the change in any particular way.
Its matchup against Mihawk was even. It also performed well against Robin, whose popularity could decline after the ban.
The deck can still hold a good place in the meta, but Mihawk's departure is not a direct advantage for it.
Want to explore the decklist and game plan? Read the Sabo OP13 Deck Guide.
Kaido OP17
Kaido benefits more from the ban.
Mihawk could manage its large Characters with the Shanks + Decken combo, which was a real problem for the deck.
Kaido still has difficult matchups against Luffy/Ace and Elbaf Luffy. Its other issue remains consistency: when it does not find its curve, its games become much more difficult.
It therefore has more room in the new format, but its own consistency issues remain.
Want to explore the decklist and game plan? Read the Kaido OP17 Deck Guide.
Luffy/Ace ST30
Luffy/Ace also benefits from Mihawk's departure. However, Robin's likely decline in popularity is not good news, since Luffy/Ace has a favorable matchup against her. It could therefore lose an opponent it was happy to face.
The deck is well positioned against Kaido and Elbaf Luffy, but has more difficulty against Xebec.
Its place will therefore depend heavily on Xebec's representation in the new meta.
Boa Hancock OP14
Boa Hancock also gains from Mihawk's ban, especially if Robin becomes less popular.
It remains slightly behind against Xebec and Kaido, although those matchups are not impossible to play. It could therefore be one of the more interesting yellow decks in the new format.
Want to explore the decklist and game plan? Read the Boa Hancock OP14 Deck Guide.
Pudding
Pudding is another deck to watch.
The Big Mom package fits naturally into the deck, thanks in part to the purple cards that let you play Katakuri earlier, as well as the 8-cost Katakuri, which can return your key characters to Active—particularly the 4,000-power Big Mom character package that gains +4,000 power during your turn thanks to the 10-cost Linlin (OP17).
With Mihawk's ban and Robin's possible decline, Pudding could become more common. It is a deck players will need to be ready for if it starts gaining popularity.
Decks That Lose the Most From the Ban
Robin OP09
Robin is directly hurt by Mihawk's disappearance.
A major part of its appeal came from its matchup against Mihawk. However, it has difficulties against several other important decks: Sabo, Luffy/Ace, Xebec, Kaido, and Elbaf Luffy.
If those decks become more common while Mihawk disappears completely, Robin's current position becomes much more difficult.
Its future deck lists may of course evolve, but with its current build, it appears to lose a great deal from this Ban List.
Want to explore the decklist and game plan? Read the Nico Robin OP09 Deck Guide.
Ace OP16
Ace finds itself in a fairly similar situation.
One of its main advantages was its ability to beat Mihawk. On the other hand, it loses to Luffy/Ace, Xebec, and Kaido, while having a good matchup against Elbaf Luffy.
Mihawk's disappearance therefore removes one of its best matchups without removing enough of its current difficulties.
Want to explore the decklist and game plan? Read the Ace OP16 Deck Guide.
Decks to Watch
Shanks OP17
Green Shanks had been overshadowed by Mihawk among green decks and could now find more room in the format.
It still has certain limitations. It can still use Shanks + Decken, but does not have the full combo used by Mihawk. It can therefore manage a large Character, such as Kaido, without necessarily being able to manage the rest of the board behind it.
Its potential will depend in particular on the new deck lists that emerge after the ban.
Want to explore the decklist and game plan? Read the Shanks OP17 Deck Guide.
Nami OP11
Blue/Yellow Nami is also being discussed as a deck that could return after Mihawk's disappearance.
In its current state, it still appears to have difficulties against the main expected decks. But its deck lists can evolve if strong players start working on the deck more.
It therefore remains a possibility to watch rather than a deck already established at the top of the format.
Teach and the Other Outsiders
Other decks remain strong enough to reappear depending on how the format evolves.
They may have several difficult matchups, especially against Xebec, but can become interesting again if certain decks start to dominate the meta.
Teach is one of the decks capable of returning and putting up good results from time to time, even if it does not appear set to dominate the format immediately.