Why couldn’t Gotenks go Super Saiyan at will?

[GreatSaiyaman123]

Every merged Saiyan can go SSJ right after forming, except Gotenks. He had to train to get the form. What’s up with that?

[super michael]

Every merged Saiyan can go SSJ right after forming, except Gotenks. He had to train to get the form. What’s up with that?

Gotenks is the first Saiyan fusion to happen, no one knew Saiyans could transformat while fused.
That is why Piccolo was confused when Goten and Trunks fused in their base form.

Goku was expecting eventually for the boys to fuse while in their SSJ form. Goku never expected Base Gotenks to trasform, let alone get SSJ3.

At this point in time Gotenks is the only character to use SSJ3 other than Goku.

[Koitsukai]

Was it ever acknowledged that they COULDN'T do it? or they just didn't do it? because if it's the latter, then maybe it was just his hubris telling him that there's no need for SS, you got this on your own. He does fight Super Buu in his base for a while.

In the manga he just returns all beaten up, we never see Gotenks failing to use SS, and I don't recall anything about him not being able to use the form, or anything implying he only used his base form(besides the anime). Only Piccolo telling them they should do it as SS. For all we know, Gotenks turned SS and still lost.
They later fuse as SS, but that doesn't necessarily mean they couldn't go SS before, it could mean they are trying to get the most out of the fusion. Perhaps, it means that fusing as SS makes for a stronger, immediate, fusion (while reducing the time limit), whereas fusing in base produces a more lasting/stable fusion, and after training there's no need for them to fuse as SS.

The real answer probably is that Toriyama forgot they could go SS.

[LoganForkHands73]

I don't think it was ever the case that they actually couldn't go Super Saiyan after fusing, it's just that Piccolo had this weird unfounded assumption that they couldn't and they just went along with it until they tried it themselves. That whole plot beat always felt very fillerific to me, there was never any good reasoning why he shouldn't be capable of transforming aside from Piccolo going S-SONNA BAKANA as always. So the "surprise" of them being able to do it after all fell completely flat. Not one of Toriyama's better twists.

[GreatSaiyaman123]

Gotenks is the first Saiyan fusion to happen, no one knew Saiyans could transformat while fused.
That is why Piccolo was confused when Goten and Trunks fused in their base form.

I think this is the case. Goku and Piccolo did want the boys to fuse while transformed, so Gotenks not transforming sounds like a weird placebo effect.

The real answer probably is that Toriyama forgot they could go SS.

I always had the opposite impression: Toriyama wanted fusions to not have the power to transform at will, but ended up changing his mind. Goku talked about the boys having to fuse as SSJs and said it was “trickier”, but gave no further explanation. Piccolo was also surprised Gotenks could even transform, and I don’t think Gotenks stays in base for that long against Super Boo.

If fusing while transformed is stronger wouldn’t everyone always fuse while transformed? Transforming after fusing always eats up a lot of Ki anyway.

I don't think it was ever the case that they actually couldn't go Super Saiyan after fusing, it's just that Piccolo had this weird unfounded assumption that they couldn't and they just went along with it until they tried it themselves. That whole plot beat always felt very fillerific to me, there was never any good reasoning why he shouldn't be capable of transforming aside from Piccolo going S-SONNA BAKANA as always. So the "surprise" of them being able to do it after all fell completely flat. Not one of Toriyama's better twists.

That bit was definitely filler. I’m not sure when Toriyama had the idea of having Boo transform, but those chapters with the boys practicing fusion while Gohan trained/had the ritual performed on him sound like Toriyama trying to catch his breath and put everyone out of the action for a minute.