Galan007
Since this topic seems to be coming up more and more, I wanted to compile all the evidence pertaining to the power of Potara fusion vs. Metamoran fusion here for future reference...
Goku first introduces the concept of Metamoran fusion, and states that the fused warrior becomes vastly stronger than the sum of its parts. He then states that the Metamors(the creators of the fusion dance) are "wimps" individually, but became "unbeatable" once they fused:
https://i.imgur.com/P7AIiri.jpg
Metamoran fusion has the stronger being suppress their power to match it with the weaker being, while Potara fusion does not require this -- though it's never mentioned that this suppressed power remains off-limits during the actual fusion:
https://i.imgur.com/pUfSDlc.jpg
When Elder Kai later introduces Potara fusion, he indicates that it is indeed more powerful than Metamoran fusion by saying "it'll work even better!":
https://i.imgur.com/7l1HY3f.jpg
It is only afterward that Elder Kai mentions how Potara is permanent, so apparently this is a different aspect than the 'greater effect' he had mentioned before... It certainly takes KibitoKai by surprise:
https://i.imgur.com/1we1rMv.jpg
Elder Kai also alludes to Potara gleaning some sort of esoteric boost when the fusees are rivals who live to outdo each other:
https://i.imgur.com/HzdIPxc.jpg
Then we have Boohan, who was not at all worried about Goku and Vegeta fusing: "the two together still don't scare me!!":
https://i.imgur.com/iejyDyH.jpg
Given that Boohan had witnessed the effects of Metamoran fusion firsthand, had absorbed a Metamoran-fused being, AND had Piccolo's knowledge at the time, it's possible that this is essentially Boo's way of saying that a theoretical Metamoran fusion between Goku and Vegeta(ie. Gogeta) would not have been able to defeat him... But then he was stomped effortlessly by Potara/Vegetto.
**That's really it from the original manga**
_________________________________________________
Next up is Weekly Jump #28 (1995), which claims Metamoran(unlike Potara, implicitly) unifies Goku+Vegeta's spirit and is therefore able to draw out their power to the max. Accordingly, it states Gogeta would defeat Vegetto in a shorter fight, but that Vegetto would win if the fight runs over 30 minutes:
https://i.imgur.com/HndStCt.jpg
https://i.imgur.com/SvL3Ldk.jpg
*Note that nothing in the manga suggests that Metamoran is better at unifying the mind/drawing out power than the Potara. Though I guess it does kind of make sense that doing a coordinated dance would unify minds better than just putting on earrings. /shrug
Next up, Daizenshuu 4's entry on the Potara (1995). This basically just repeats Elder Kai's vague "like Fusion, but the effect is greater" statement, with no further clarification. The lack of a time limit is again seemingly separate from the 'greater effect':
https://i.imgur.com/X9WZzJE.jpg
https://i.imgur.com/kuqNCMN.jpg
Then we get Daizenshuu 7's Potara entry (1996). This one flat-out says Potara fusion has greater power than Metamoran fusion:
https://i.imgur.com/me2b6Jx.jpg
https://i.imgur.com/5wmIRU3.jpg
Next up, GT Perfect Files Vol.2 (1997). This describes SSJ4 Gogeta/Metamoran as having power "tens of times greater than a single SSJ4":
https://i.imgur.com/Djp7ve8.jpg
https://i.imgur.com/Nz1JjQ9.jpg
In fact, Toei's official GT site says precisely the same thing about SSJ4 Gogeta, with precisely the same picture as well:
https://i.imgur.com/R3VRBfA.jpg
https://i.imgur.com/Nz1JjQ9.jpg
(that sort of boost will come up again.)
The Super Exciting Guide (2009) describes the power-up from the Potara as so incredible "it's like multiplying the two characters' power levels together!" The caption even helpfully reads "Goku x Vegeta = Vegetto":
https://i.imgur.com/mZ76Brx.jpg
However, the SEG also describes Metamoran fusion as multiplying the two fusees' powers together:
https://i.imgur.com/PaCxMRk.jpg
The Chouzenshuu 4 Potara entry (2013) is pretty much just a reprint of the Daizenshuu 7 entry, and says precisely the same thing about Potara giving more power than Metamoran:
https://i.imgur.com/98C0aYe.jpg
https://i.imgur.com/5wmIRU3.jpg
Jumping all the way to DBS ep.114 (2017), Vados describes the Potara as increasing Caulifla/Kale's power by "tens of times", which you may recall is the same description earlier given to SSJ4 Gogeta compared with a regular SSJ4:
https://i.imgur.com/1fbZjD5.jpg
https://i.imgur.com/ZRtAZq9.jpg
The DBS Warrior Sticker Wafers Z (2018), put out cards listing the power of SSB Vegetto at 9300 and SSB Gogeta at 9600:
https://i.imgur.com/OZMbgJB.jpg
https://i.imgur.com/Mvj79Kz.jpg
Certainly not an irrefutable source, but it may as well be mentioned, lol.
And Weekly Jump (2018) has a DBS: Broly promo piece describing Gogeta and Vegetto as "equally-matched ultimate trump cards!!":
https://i.imgur.com/PnnUGcC.jpg
https://i.imgur.com/7wgGIIT.jpg
Additionally, Gogeta also talks about the power of Metamoran fusion in the Broly film...
Gogeta: "I am Gogeta... The fusion of Goku and Vegeta."
Freeza: "Fusion?"
Gogeta: "You were dead for a long time, so you wouldn't know. This is a tremendous power-up that goes beyond merely adding their two powers together."
https://i.imgur.com/ra4AgVa.jpg
https://i.imgur.com/EMpLues.jpg
https://i.imgur.com/McPJqHj.jpg
https://i.imgur.com/wNByHPN.jpg
https://i.imgur.com/uALkvKZ.jpg
More confirmation that fusion isn't just a 1+1=2 sort of thing... And given the power Gogeta displayed in this film(it could easily be argued that BASE Gogeta > SSB Goku/Vegeta, for example), it does indeed seem more akin to multiplying their powers together, as previous guidebooks have stated.
_________________________________________________
**Regarding the time-limits of fusion**
It was originally stated that Metamoran lasts 30 minutes:
https://i.imgur.com/OxnU3ET.jpg
But we later learned that the power of SSJ3 shortened the fusion time to just 5 minutes:
https://i.imgur.com/cFt3ePV.jpg
And for what it's worth, in GT the power of SSJ4 shortened the fusion time to less than 10 minutes:
https://i.imgur.com/glpRQam.jpg
https://i.imgur.com/7GLF33y.jpg
https://i.imgur.com/xarTKM9.jpg
https://i.imgur.com/q5AvItQ.jpg
However, as of the recent Broly film it would seem that the fusion time of Metamoran no longer decreases as the warrior becomes more powerful. It lasts a full 30mins regardless:
https://i.imgur.com/n3RciOg.jpg
https://i.imgur.com/8vPj0U3.jpg
Where Potara is concerned, we were originally led to believe that it was absolutely permanent and could never be undone:
https://i.imgur.com/1we1rMv.jpg
But as of DBS, we learned that Potara fusion is only permanent when used by Kaioshin. If used by mortals, Potara only lasts a maximum of 1 hour:
https://i.imgur.com/7awNrT4.jpg
https://i.imgur.com/5Fw6ZtC.jpg
https://i.imgur.com/6BnzDvQ.jpg
https://i.imgur.com/gFbqLV7.jpg
https://i.imgur.com/bp1vPHv.jpg
However, in Potara's case the fusion time for mortals DOES decrease when the warrior is hyper-powerful. During the Zamasu arc, Vegetto was only able to exist for a few minutes before the fusion became unstable and timed-out. Gowasu attributed this solely to the power he was generating:
https://i.imgur.com/uvkgumW.jpg
https://i.imgur.com/Wzufxva.jpg
https://i.imgur.com/p9B5nIr.jpg
https://i.imgur.com/cOkx6SQ.jpg
https://i.imgur.com/OUsTapH.jpg
_________________________________________________
Personally, I think Potara was intended to be superior to Metamoran back when the material was originally written, but it seems like they are being treated as equal powerups these days... Which I don't really have a problem with(makes things a bit more cohesive that way, imo.) Although it would seem that in Goku and Vegeta's case(because they are so powerful), Metamoran now lasts longer than Potara for them.
Goku first introduces the concept of Metamoran fusion, and states that the fused warrior becomes vastly stronger than the sum of its parts. He then states that the Metamors(the creators of the fusion dance) are "wimps" individually, but became "unbeatable" once they fused:
https://i.imgur.com/P7AIiri.jpg
Metamoran fusion has the stronger being suppress their power to match it with the weaker being, while Potara fusion does not require this -- though it's never mentioned that this suppressed power remains off-limits during the actual fusion:
https://i.imgur.com/pUfSDlc.jpg
When Elder Kai later introduces Potara fusion, he indicates that it is indeed more powerful than Metamoran fusion by saying "it'll work even better!":
https://i.imgur.com/7l1HY3f.jpg
It is only afterward that Elder Kai mentions how Potara is permanent, so apparently this is a different aspect than the 'greater effect' he had mentioned before... It certainly takes KibitoKai by surprise:
https://i.imgur.com/1we1rMv.jpg
Elder Kai also alludes to Potara gleaning some sort of esoteric boost when the fusees are rivals who live to outdo each other:
https://i.imgur.com/HzdIPxc.jpg
Then we have Boohan, who was not at all worried about Goku and Vegeta fusing: "the two together still don't scare me!!":
https://i.imgur.com/iejyDyH.jpg
Given that Boohan had witnessed the effects of Metamoran fusion firsthand, had absorbed a Metamoran-fused being, AND had Piccolo's knowledge at the time, it's possible that this is essentially Boo's way of saying that a theoretical Metamoran fusion between Goku and Vegeta(ie. Gogeta) would not have been able to defeat him... But then he was stomped effortlessly by Potara/Vegetto.
**That's really it from the original manga**
_________________________________________________
Next up is Weekly Jump #28 (1995), which claims Metamoran(unlike Potara, implicitly) unifies Goku+Vegeta's spirit and is therefore able to draw out their power to the max. Accordingly, it states Gogeta would defeat Vegetto in a shorter fight, but that Vegetto would win if the fight runs over 30 minutes:
https://i.imgur.com/HndStCt.jpg
https://i.imgur.com/SvL3Ldk.jpg
*Note that nothing in the manga suggests that Metamoran is better at unifying the mind/drawing out power than the Potara. Though I guess it does kind of make sense that doing a coordinated dance would unify minds better than just putting on earrings. /shrug
Next up, Daizenshuu 4's entry on the Potara (1995). This basically just repeats Elder Kai's vague "like Fusion, but the effect is greater" statement, with no further clarification. The lack of a time limit is again seemingly separate from the 'greater effect':
https://i.imgur.com/X9WZzJE.jpg
https://i.imgur.com/kuqNCMN.jpg
Then we get Daizenshuu 7's Potara entry (1996). This one flat-out says Potara fusion has greater power than Metamoran fusion:
https://i.imgur.com/me2b6Jx.jpg
https://i.imgur.com/5wmIRU3.jpg
Next up, GT Perfect Files Vol.2 (1997). This describes SSJ4 Gogeta/Metamoran as having power "tens of times greater than a single SSJ4":
https://i.imgur.com/Djp7ve8.jpg
https://i.imgur.com/Nz1JjQ9.jpg
In fact, Toei's official GT site says precisely the same thing about SSJ4 Gogeta, with precisely the same picture as well:
https://i.imgur.com/R3VRBfA.jpg
https://i.imgur.com/Nz1JjQ9.jpg
(that sort of boost will come up again.)
The Super Exciting Guide (2009) describes the power-up from the Potara as so incredible "it's like multiplying the two characters' power levels together!" The caption even helpfully reads "Goku x Vegeta = Vegetto":
https://i.imgur.com/mZ76Brx.jpg
However, the SEG also describes Metamoran fusion as multiplying the two fusees' powers together:
https://i.imgur.com/PaCxMRk.jpg
The Chouzenshuu 4 Potara entry (2013) is pretty much just a reprint of the Daizenshuu 7 entry, and says precisely the same thing about Potara giving more power than Metamoran:
https://i.imgur.com/98C0aYe.jpg
https://i.imgur.com/5wmIRU3.jpg
Jumping all the way to DBS ep.114 (2017), Vados describes the Potara as increasing Caulifla/Kale's power by "tens of times", which you may recall is the same description earlier given to SSJ4 Gogeta compared with a regular SSJ4:
https://i.imgur.com/1fbZjD5.jpg
https://i.imgur.com/ZRtAZq9.jpg
The DBS Warrior Sticker Wafers Z (2018), put out cards listing the power of SSB Vegetto at 9300 and SSB Gogeta at 9600:
https://i.imgur.com/OZMbgJB.jpg
https://i.imgur.com/Mvj79Kz.jpg
Certainly not an irrefutable source, but it may as well be mentioned, lol.
And Weekly Jump (2018) has a DBS: Broly promo piece describing Gogeta and Vegetto as "equally-matched ultimate trump cards!!":
https://i.imgur.com/PnnUGcC.jpg
https://i.imgur.com/7wgGIIT.jpg
Additionally, Gogeta also talks about the power of Metamoran fusion in the Broly film...
Gogeta: "I am Gogeta... The fusion of Goku and Vegeta."
Freeza: "Fusion?"
Gogeta: "You were dead for a long time, so you wouldn't know. This is a tremendous power-up that goes beyond merely adding their two powers together."
https://i.imgur.com/ra4AgVa.jpg
https://i.imgur.com/EMpLues.jpg
https://i.imgur.com/McPJqHj.jpg
https://i.imgur.com/wNByHPN.jpg
https://i.imgur.com/uALkvKZ.jpg
More confirmation that fusion isn't just a 1+1=2 sort of thing... And given the power Gogeta displayed in this film(it could easily be argued that BASE Gogeta > SSB Goku/Vegeta, for example), it does indeed seem more akin to multiplying their powers together, as previous guidebooks have stated.
_________________________________________________
**Regarding the time-limits of fusion**
It was originally stated that Metamoran lasts 30 minutes:
https://i.imgur.com/OxnU3ET.jpg
But we later learned that the power of SSJ3 shortened the fusion time to just 5 minutes:
https://i.imgur.com/cFt3ePV.jpg
And for what it's worth, in GT the power of SSJ4 shortened the fusion time to less than 10 minutes:
https://i.imgur.com/glpRQam.jpg
https://i.imgur.com/7GLF33y.jpg
https://i.imgur.com/xarTKM9.jpg
https://i.imgur.com/q5AvItQ.jpg
However, as of the recent Broly film it would seem that the fusion time of Metamoran no longer decreases as the warrior becomes more powerful. It lasts a full 30mins regardless:
https://i.imgur.com/n3RciOg.jpg
https://i.imgur.com/8vPj0U3.jpg
Where Potara is concerned, we were originally led to believe that it was absolutely permanent and could never be undone:
https://i.imgur.com/1we1rMv.jpg
But as of DBS, we learned that Potara fusion is only permanent when used by Kaioshin. If used by mortals, Potara only lasts a maximum of 1 hour:
https://i.imgur.com/7awNrT4.jpg
https://i.imgur.com/5Fw6ZtC.jpg
https://i.imgur.com/6BnzDvQ.jpg
https://i.imgur.com/gFbqLV7.jpg
https://i.imgur.com/bp1vPHv.jpg
However, in Potara's case the fusion time for mortals DOES decrease when the warrior is hyper-powerful. During the Zamasu arc, Vegetto was only able to exist for a few minutes before the fusion became unstable and timed-out. Gowasu attributed this solely to the power he was generating:
https://i.imgur.com/uvkgumW.jpg
https://i.imgur.com/Wzufxva.jpg
https://i.imgur.com/p9B5nIr.jpg
https://i.imgur.com/cOkx6SQ.jpg
https://i.imgur.com/OUsTapH.jpg
_________________________________________________
Personally, I think Potara was intended to be superior to Metamoran back when the material was originally written, but it seems like they are being treated as equal powerups these days... Which I don't really have a problem with(makes things a bit more cohesive that way, imo.) Although it would seem that in Goku and Vegeta's case(because they are so powerful), Metamoran now lasts longer than Potara for them.