No matter how hard developers try to balance the game, there will always be a meta that will come out, especially in direct games like MultiVersus. Whether or not this meta is healthy for the game depends on a variety of factors. Unfortunately, the Warner Brothers-oriented platformer has a bit of a crisis when it comes to the meta set by the latest series of MultiVersus change in balance.
The developers at Player First Games have largely left MultiVersus' great balance of two patches per season: start and midseason, lined up perfectly with the addition of all new characters. Season 3's final balance patch saw the rise of a special character, capable of accurate and unstoppable combos that level opponents at 0%.

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MultiVersus Stage List
MultiVersus has many stages, but some are simply adjusted compared to others in the list; here's the full breakdown.
The Banana Guard has been dominant since the mid-season 3 update
The Banana Guard Problem in MultiVersus
Banana Guard has been a controversial character since his place on the roster became public knowledge. But his latest batch of fans in the middle of the season has made him an absolute monster when it comes to success. The most recent changes to the game have made him one of the most dangerous fighters on the list with some of the most powerful kills.
For other characters, this meta may not be a problem. After all, there will always be some characters that will be better than others. This is the nature of video games in general. Regardless of how one feels about his inclusion in the list as a joke, a fighter like Banana Guard being the top pick in the game is not a healthy state for fighting game.
Why Meta Guard Banana is not healthy for MultiVersus
No one avoids meta in general; there will always be one, no matter how hard the developers try to balance everything. In a perfect world, a game's meta should have the most powerful characters, weapons, and equipment locked behind a high-level floor – that is, the most powerful things in the game are should be difficult to use. This philosophy rewards players who have spent time and practice with the game, and ultimately encourages the rest of the player base to improve themselves.
As for the MultiVersusArya is a good example of this. He has been strong since the beginning of the game, but he will not progress unless the player has the basics of his kit, combo string and the whole game. His damage output is very high when played well, but he's still light and easy to kill if the player doesn't know what he's doing. Arya has some of the highest powers out there MultiVersusbut only if the players put in the hours and study, which means that there won't be a million Aryas destroying people regularly.
Banana Guard, on the other hand, is designed as a very friendly character. He has simple, high-damage moves, easy combo strings, and as anyone who's fought him can tell, a very forgiving box for all of his attacks. There is definitely a place for such a character as Banana Guard is meant to introduce players to the game. It's very easy to pick up and do well right out of the gate; the kind of character where someone could hand their little brother the controller and they'd be able to pick it up easily and have a great time. The problem is making this type of character too effective. Then the game has situations where even a player who invests money can become a threat with little effort or show of skill.
The reign of the banana guardians is unlikely to last long. The Powerpuff Girls are launched MultiVersus with 0 to death combos at the beginning of season 3 and the developers solved this problem in two days. But of course a simple character like Banana Guard can't stay that long. Otherwise, the devs risk damaging the game's long-term appeal and competitive landscape.