The first episode of Dragon Ball Daima reveals the setting of the series in the Dragon Ball timeline. Set almost immediately after the Buu Saga of Dragon Ball Z, the Z Fighters begin the anime with the same power levels they had at the end of that arc. This changes after Gomah makes a wish on the Dragon Balls and turns all of the Z Fighters into children.

Goku and the other Z Fighters were weakened after being turned into children in Dragon Ball DAIMA. While they are still powerful fighters, most will not be able to perform the same feats as adults. However, due to the origin of their abilities, some members of Team Dragon are less hindered than others, making them much stronger than characters who were previously much stronger than them.
The Strongest Child Characters in Dragon Ball DAIMA
Hybis is a loyal ally of the ruler of the third demon world.
Hybis is another character whose age is never stated. However, this character definitely acts like a child most of the time, considering his arguments and reasoning about everything. While he may be a loyal soldier of Kadan, Hybis cares more about food than anything else.
Hybis doesn't seem to be much of a real fighter. He can control enough ki to fly, but not much else. Of course, it's impossible to judge his strength since most of the opponents in DAIMA are above Super Saiyan level, so he's probably the weakest character on this list.
Panzy is a child in the demon world
Panzy is 82 years old, but in a world where living to 1000 years old is the norm, she is still considered a child to most people, especially in her kingdom. As the daughter of the leader of the Third Demon Realm, she was famous for her fighting spirit even before meeting Goku. She fought against the Gendarmerie and their brutal oppression of the common people.
However, compared to many other fighters in Dragon Ball DAIMA, Panzy is not actually that strong. Instead, she relies on the technology she has created, from her explosive Wasabi Bombs to her ki blaster. Panzy is stronger than a human like Bulma, but weaker than the average Z Fighter.

Master Roshi is a little older than the other children.
Gomah's wish had a particular effect on Master Roshi. While most of the Dragon Team turned into children, and Goten, Trunks, and Dende became infants, Goku's original mentor became a teenager. The character's less "chibi" body meant that Roshi could still put his "centuries" of martial arts training to good use.
Even at the end of the Saiyan Saga, let alone the Buu Saga, Master Roshi was no match for any of the other Z-Warriors. However, he was still a formidable warrior, capable of destroying Earth's moon. And thanks to characters like Gohan, Tien, and Chiaotzu being absent from Trunks' birthday party, Roshi is now one of the strongest child characters in DAIMA.
Yamcha is almost as strong as Goku
By the end of Dragon Ball Z, Yamcha is one of the strongest living beings known to exist in the Dragon Ball universe. The series' lovable punching bag may be a joke to many, but he's no weaker than Krillin or Tien. Of course, that's still nothing compared to the non-human Z Fighters.
As a teenager, Yamcha was able to hold his own against a starving Goku for a short time. Now that they're both kids again, the gap between them, while still large, is perhaps the smallest it's been since they first met. Unfortunately for Yamcha, not only is he now stuck in a body that doesn't know how to fight, but he also retired as a warrior before the Buu Saga.
Krillin is still the strongest human, even in his child form.
Krillin isn't even affected as much by being shrunk as other fighters, as he's used to being short.
Like everyone else, Krillin is now weaker than he was as an adult. However, Krillin's most famous attack doesn't rely on raw strength. The Destructo Disc can theoretically cut through anyone and anything, and the fact that Krillin is smaller than normal doesn't affect the technique.