SSJ4 Vegito

Well maybe but they still could easily pull characters from wherever they want since they wanted to make Goku the hero. We don't know what goes on in the guys head's who make this so I don't see why we have to for "Outside-universe" explanations. They could have pulled them from the Time Chamber it's their movie and they can do whatever they want. Also you clearly notice in the scene after Vegeta is first grabbed by Piccolo to go and fight. Gohan is blasted aside and Broly (With an angry look on his face) punches Goku, and then the screen goes back to Vegeta & Piccolo arguing. No I suppose you'd say "Well Piccolo isn't stronger than Vegeta in the Cell Games" well that may be true but I find it quite possible that Piccolo was in the ROSAT for most of the Movie so I think Vegeta and Trunks are at their level when they fought Perfect Cell. Piccolo didn't do too much worse against the Cell Juniors than Vegeta & Trunks did, and Vegeta (Cell Games) thought he could beat Cell (The one who creamed him before) so I could easily see Piccolo (Movie 8) being better than Vegeta (Movie 8).
As I mentioned before Goku was hit by Broly (Who has a mad expression on his face) and then when Goku is knocked into a building and says "This guy is really something else" Broly blasts him one time (With a serious look on his face) now we never see Gohan again after he's blasted away in the scene where Piccolo is nagging Vegeta so really when Broly had a pissed off expression for those instances then Goku is stronger since he lasted longer. We might not know who he was going harder on and who he wasn't but when you see Goku get with a serious punch and a blast and still have alot more energy to keep fighting, then he could easily be the strongest warrior. Even in the first round he has the same expression on his face when he fights them before Piccolo shows up and yet Goku STILL lasts longer. So really theres nothing to suggest that he fought them each with a certain level of power. This is of course my opinion, but I made this thread to not have another discussion regarding the Z Fighters power in Movie 8 & Movie 10 so I was aiming to avoid it but oh, well.
However Broly is right about one thing combining Base Vegeta (Half power) & the others half power was really not the case I think they simply needed some reason for Broly to be defeated. However I think that they had more fight in them but since they already tried ganging up on him Piccolo knew it wouldn't work so maybe they just decided to combine they're powers.