Not all requests can be granted Dragon Ball
Dragon Ball though is a shonen manga that emphasizes the fight, but is basically an adventure of collecting Dragon Ball. If we remember the story Dragon Ball was originally an adventure of Son Goku, Bulma, and his friends to collect the Dragon Ball that supposedly we can make a request to be granted the Dragon Ball. That later the fight should be the impact of the Dragon Ball quest adventure.
Although Shenron promises to fulfill the request, not all requests are granted by Dragon Ball. This is because the ability of Shenron is limited by the ability of its creator, Kami-sama. If the request exceeds Kami-sama's ability, he will reject it and ask for another request.
Beyond its limitations, Dragon Ball itself has a wide demand range. Call it like giving panties as requested Oolong, revive the dead, to live eternally.
Here is a request that Dragon Ball can not answer. Of course the one discussed here is the Dragon Ball Earth where the dragon god is Shenron, and Dragon Ball Namek with the Dragon god of Porunga. Given that Super Dragon Ball is said to be able to grant any request.
Revives the dead natural.
Dragon Ball can indeed turn on the dead, but still there are conditions. Revived deaths are forced deaths, such as death from being killed, or exploding planets. But Dragon Ball can not turn on people who die naturally, for example because of age or because of deadly disease.
An example of a reviving request for the dead is reviving Son Goku who died of a viral heart attack on the Future Trunks timeline. Because he died by illness, Son Goku could not be revived so he never resisted the Android attack.
Dragon Ball also can not revive Grand Elder Guru from Namek because of its age. He was alive again because of Frieza's actions that killed his children put him under stress and hastened his death. He became alive for a while, before his old age ended his life.
Raises people who do not want to live again
When Cell saga ends, we know that Son Goku was killed by Cell suicide. Therefore Son Goku should be revived by Dragon Ball. But he (his spirit) refused to be revived because he wanted to freely practice in the afterlife. If the person does not want to be revived, then Dragon Ball can not turn it on.
One of the origins of Piccolo's arrival to Earth is because he originally lived on Planet Namek. But once the planet is experiencing climate change to kill life on this planet. Piccolo became one of the Namekian who fled when climate change occurred, unfortunately the plane he ran was damaged so he came up with minimal information.
Climate change itself can not be changed by Dragon Ball because climate change is something beyond the ability of its creator, in this case is the Grand Elder Guru for Dragon Ball at Planet Namek. So that Namekian fate when climate change occurs not far away as the fate of refugees as it should be.
Reliving Android 16
In this case there are inconsistencies from Akira Toriyama, so the possibility of this theory may not apply.
Post Cell Saga, Android 17 and Android 18 live again, but not with Android 16. It's said this is because Android 16 is a pure robot, unlike Android 17 and Android 18 which is half human.
This is because android technology seems beyond God's intelligence, then Android 16 can not live again.
However this is inconsistent with the live comeback of Arale and Android 8. Although they are both pure robots, yet they can still live again for example after the Earth was destroyed by Buu. So which one is true?
DRAGON BALL Z DOKKAN BATTLE
BANDAI NAMCO Entertainment Inc.
Looking for Super Dragon Ball
One of Bulma's efforts and his friends looking for Super Dragon Ball is by summoning Shenron. But the universe is too broad for Shenron even he does not know the existence of the Super Dragon Ball. Moreover, the thing outside the universe in which he resides, in this case outside of Universe 7, is beyond the power of Shenron.
Killing a person stronger than his creator
When Saiyan saga, had implied to ask the Dragon Ball to kill Vegeta and Nappa. But this can not be done because Vegeta and Nappa are stronger than the creators of Dragon Ball, Kami-sama
This makes the request of killing people so difficult to grasp, given that the next god is Dende who never used his power to fight.
Edited by Doni Jaelani