Gege Akutami's Jujutsu Kaisen is a good series. It has complex characters, great action, and a well-designed power system. All of these things go together to both embrace and subvert the common tropes of battle manga under the Shōnen Jump banner.
It's especially important for Jump artists to ensure that the battle aspect of their manga is unique. Many of the tropes of the shonen battle have been done to death; they make so many otherwise-distinctive manga feel as though they're ripping off Dragon Ball Z. JJK falls for this sometimes, too, but there is at least one aspect of shonen battles that it's been able to find a clever workaround for. The trope is still invoked, but it's done so in a way that otherwise would make little sense. Of all the shonen battle mangaka, Akutmi is the only one to figure out how to justify characters announcing their obscure abilities in the middle of a fight.
In most other battle manga, having the characters announce their abilities is a bad idea on all fronts. For one thing, it's a bad strategy on the part of the combatant to announce their ability. One of the biggest deciding factors of a fight is the ability to catch one's opponent by surprise; if one gives away their ability ahead of time, their opponent can plan around it and render that element of surprise useless. The only reason one would have to announce their ability is if they thought it wouldn't make a difference, an arrogant play used by a lot of shonen antagonists.
Another issue with having characters announce their abilities is that it's often a sign of bad writing. It's a lazy method of expositing a complicated power that would certainly need a long explanation or a diagram to understand. The problem is that there's almost no way to write such an explanation into a story that comes off as natural-sounding dialogue.
The best fix writers have found for this trope is to have the opponent figure out the mechanics of the ability. By steadily revealing more about the ability in this manner, the author gets across necessary information at a natural pace. It also helps put the audience in the shoes of that character; both parties learn about the ability at roughly the same pace. This form of revealing complex abilities is employed by series like JoJo's Bizarre Adventure, but JJK actually has another method that's wholly unique to its own story.
In JJK, cursed techniques receive a significant boost in power when their users announce them. It's a brilliant double-edged sword. On one hand, the power boost guarantees that they'll be able to secure the win if they can land a clean hit on a strong opponent. On the other hand, that decisive blow becomes harder to land as the opponent knows what to look out for. It's an understandable tradeoff to explain one's abilities that comes with all sorts of pros and cons.
Akutami has truly revolutionized battle manga with his discovery. Not only has he found justification for one of the genre's oldest tropes, but he's raised the standard of quality for future Jump mangaka. Any battle shonen published after JJK are encouraged to find their own solutions to this and other tropes. Meanwhile, Akutami can have all the beef jerky he wants.
