Minimum power level required for planet-busting?

[Tensa Zangetsu]

But then, why was he not confident of taking Old Piccolo Daimao even along with Tenshinhan's help? He even says his younger self won't be a match for him.

...Because of the explanation Herms just offered. His buff states grants him a huge amount of power, but it's useless in an actual fight. King Piccolo wouldn't just stand there and let Roshi charge up and hit him with a Kamehameha.

Tien and the others could hold him off for a while...like how Piccolo held off Frieza while Goku charged up his spirit bomb

[Kamiccolo9]

I think Roshi blowing up the Moon is a real bump in the progression of power depictions. That's enough power to wipe out all life on Earth with a single attack, even if the planet itself would technically survive, and yet Daimao is only as powerful as a nuclear weapon and the most we see him (or anyone before Freeza, for that matter) blow up is the size of a city or an island? Maybe Earth's Moon in Dragon Ball is just really fragile.

I like to try and partially explain that away by saying that maybe Kame-sennin's beefy form is similar to Super Saiyan Grade III: a "power-weighted" form that makes his power shoot way, way up but kills his speed, making it unsuited for battle. On top of that, his Max Power Kamehameha is probably similar to attacks like the Makankosappo, ones that are leagues stronger than the character's regular attacks but take a long time to charge. Long story short, when Kame-sennin beefs up and fires his Max Power Kamehamaeha, perhaps he technically is much more powerful than Piccolo, but he'd never be able to land an attack on Piccolo in a real one-on-one fight, similar to Trunks vs Cell. It is suggestive that the only times in the main series where we ever see Kame-sennin use his beefy form is when firing attacks at large, immobile objects.

But then, why was he not confident of taking Old Piccolo Daimao even along with Tenshinhan's help? He even says his younger self won't be a match for him.
Infact he wasn't even confident of taking the red ribbon army.

I also think the moonbusting part is an outlier because the Kamehameha can't reach the moon in seconds.

Except, you know, it did.

]Piccolo daimao was clearly boasting, and we know his best attacks could only destroy cities.
The daizenshuu even says his power rivals only that of a small nuke.

He was probably thinking of destroying the world one city at a time, instead of one-shotting the entire planet in a single blast like Vegeta.

Just because he was bragging about it doesn't mean he was lying. And if Roshi was capable of blowing up the moon, then Daimao, who was much more powerful than Roshi was, would clearly have more power than he. Seeing as a small nuke couldn't destroy the moon, you would have to reconcile that statement (can I get an exact citation for that, by the way?) by saying that it was referring specifically to the attack Daimao used to destroy that city (and again, who says that was his best attack?) and not referring to his full power, as, again, he was much stronger than the guy who blew up the moon.

And I'm not saying that Daimao could blow up the Earth, only that such a feat being within his power would not contradict anything that happens later in the series. The gaps between the consecutive villains allow for a huge area of potential "planet-busting" power levels. We don't have enough information to set a minimum.

Roshi blowing up the moon is an outlier.

He can't even beat the red ribbon army, and guys stronger than him like Tao get destroyed by grenades.

And
Chapter: 161, P13.4
Yajirobe: “But man, what kind of a guy are you?...I can’t believe you beat someone who could blow a city to pieces…”

..implying someone stronger than Roshi, like Yajirobe can't tank city level attacks

Or possibly it just means that Yajirobe isn't all that experienced when it comes to ki attacks. Which is understandable, seeing as he can't perform them himself. And as for Roshi's blast being an outlier, so what? Who's to say that Daimao couldn't do the same thing? I mean, we see all the time that bulking up and forcing power out isn't that hard to do (see, Roshi, Freeza, Cell, Trunks, Goku).

[rereboy]

We don't know if Vegeta was really going to blow up the Earth for good. Vegeta can be cocky, but I don't think he's that cocky enough to kill himself along with the Planet.

He would only be in trouble if the planet exploded instantly. As long as he has a few minutes to get out of the planet, there's no problem.

Wasn't Vegeta using Galick gun that put him around 24,000?

At that time Vegeta didn't know how to control his Ki so he can't go beyond his stated power level : 18.000.

However, at that time, he had already been hurt and Goku was also very hurt by the use of the Kaioken, so their max power at that time had already dropped from the max they could do uninjured.

[The Monkey King]

I think Roshi blowing up the Moon is a real bump in the progression of power depictions. That's enough power to wipe out all life on Earth with a single attack, even if the planet itself would technically survive, and yet Daimao is only as powerful as a nuclear weapon and the most we see him (or anyone before Freeza, for that matter) blow up is the size of a city or an island? Maybe Earth's Moon in Dragon Ball is just really fragile.

According to the Daizenshuu Papaya island rivals a small continent in size and 23rd BT Piccolo destroyed it while low on ki:

Spoiler:

Also Nappa destroyed a continent sized area of the Earth by lifting 2 fingers:

Spoiler:

But then you have to start getting into defintions. Even with a bit less than 2.24 x 10^32 joules, you could still shatter the planet; the catch is just that the pieces would then crash back together. That would still kill everything on Earth and most likely turn the entire planet inside out though, right? Does that count as "planet-busting"? Personally, I think that if Vegeta could only do that much but not completely reduce the Earth to space-dust, it would still easily fit his boast of destroying the planet.

I dunno, Vegeta specifically stated he was going to reduce the Earth to space dust:

Chapter: 231 (DBZ 37), P4.2/P6.2/P12.5
Context: Vegeta prepares to fire the Gyarikku-Ho
Vegeta: “Dodge this if you can!!!! Even if you save yourself, the Earth will be smashed to pieces!!!!! [ ] You’ll never block my Gyarikku-Ho…!!!! Turn to space dust together with the Earth!!!!!”
Goku: “x4!!!!!” *he uses the Kaio-ken x4*

[Tensa Zangetsu]

Except, you know, it did.

Just because it happened doesn't mean its consistent with the series.

Goku struggling with 40 tons during the Buu saga also happened. Doesn't mean its not an outlier.

Or possibly it just means that Yajirobe isn't all that experienced when it comes to ki attacks. Which is understandable, seeing as he can't perform them himself.

The thing is, he is afraid of KPs blast though characters weaker than him should be able to blow up the moon.

If Roshi was truly a moonbuster, Yajirobe would simply laugh at city level attacks as he could tank it with his face without getting a scratch. He should be confident that a city level attack won't do crap to him.

Portrayal and feats, both have KP at city level apart from the daizenshuu statements..

And as for Roshi's blast being an outlier, so what? Who's to say that Daimao couldn't do the same thing? I mean, we see all the time that bulking up and forcing power out isn't that hard to do (see, Roshi, Freeza, Cell, Trunks, Goku).

Because Kamehameha is an attack that multiplies the users PL while KP's explosive demon wave doesn't. Tri beam and special beam cannon are the only attacks which do so along with KHH.

When Goku used his KHH against Raditz, his PL spiked up to 900+. Raditz was even surprised that Goku had attacks that could raise his PL.

[Friezacooler]

figure out the minimum power level you need to break through a brick wall, the stamina endurance and than you will find out how long it will take you to keep punching/ busting a planet over time.

[Polyphase Avatron]

figure out the minimum power level you need to break through a brick wall, the stamina endurance and than you will find out how long it will take you to keep punching/ busting a planet over time.

I'm pretty sure if you did it that way you would end up with some ridiculously huge number.