No! I believe Boo Arc SSJ3 Gotenks is four times stronger than Boo Arc SSJ3 Goku.
That's not what you said down there. And don't those two statements mean the same thing?
Yes, Goku put up a fight against him but Super Janemba was not fighting with his true power. Super Janemba true power is when he powering up against Gogeta.
We never got a confirmation that he powered up; considering Janemba's personality (a feral demon), I find it very unlikely that he let himself get hit, or that he can even suppress his power. He clearly doesn't care about a good fight; Goku was able to oppose him. SS2 Vegeta wasn't, so Janemba just one-shotted him. He was just flaring his aura in defiance.
That's also rather hypocritical.
No one noted a power drop in Hildegarn = he must not have gotten weaker
No one noted a power up in Janemba = doesn't matter, he still got stronger
As I said, Janemba is a much closer counterpart to Pure Buu.
Ultimate Gohan never showed power to defeat Hildegarn. Full power U. Gohan punches the lower half part of Hildegarn's body ( who is weaker than his complete body and even more weaker than his second form ) with 0 damage. SSJ3 Gotenks dominates in skill and speed but never in power. Hildegarn super power is far superior than his own speed and technique.
It might just be a result of Hildegarn's body reacting to hits a different way. Like Buu.
He was able to force Hildegarn into a transformation. You can't seriously tell me you think Hildegarn can one-shot him at that point? Because he would if his bottom half was stronger than Gohan.
Yes, the tail is an important part of Hildegarn body but we do not see anyone say that it has lost much of his power. Maybe he lost power but not much. I do not remember well but Freezer lost his tail and no power lost.
He loses a major part of his biology that we earlier saw was incredibly important (it's how he ate), vomits blood immediately after it is severed, and is suddenly unable to one-shot someone far weaker than the guys he just beat. Do they even need to tell us? Did we need to be told that Freeza's power dropped when he was cut in half?
Also, I'd like to note the similarities of this scene to Yajirobe cutting Vegeta's tail.
In this movie the thing is different. SSJ3 Gotenks did nothing to stop the blow while Goku was prepared to take hits.
That wouldn't matter, since Gotenks is just that much stronger. Also, he was fully expecting a hit.
Just for the record: I don't think SS3 Gotenks and Ultimate Gohan are 5-10 times stronger than SS3 Goku or anything like that, because I don't think that fits the story at certain points (the implications of the South Kaioshin absorption, the Genki Dama, SS3 Goku apparently being at least useful as a lacky against Buutenks, SS Gotenks hurting Super Buu with a headbutt, a certain guidebook making the SK absorption sound like addition, a guidebook saying Evil Buu + Good Buu is only "somewhat weaker" than Buff Buu, et cetera). More like 2-3 times stronger. But a Buutenks/Buuhan tier guy like Hildegarn would still one-shot him if he was at full power.