Again, Cell.
It's already been mentioned in other same questions.
Super Perfect Cell
The Word Came From A Sciencetist
Two scientists came up with The Cell Theory. It was in 1839, Matthias Schleidan and Theodor Schwann, two German Biologists came up with this theory.
Hooke looked at the cell in a piece of cork and came up with the name ' cell ' because the square plant cell he was looking at reminded him of monk's living/praying quarters.
Master myslon invented the cell theory and came up with it
In the first broly movie, broly was fought during in the middle of the ten days before the cell games. In the second movie, he got weaker back when he fought cell because after cell died, he didn't train for 7 years
Cell, even his 2nd form will gave Broly trouble. Broly can beat Imperfect Cell which is his possible chance. But Perfect Cell will kill Broly easily, without going full power. Goku and Z-fighters from Cell Games Saga can easily and possibly beat Broly than their Movie 8 counterparts. (When I saw this question, A Broly fanboy answered a question inaccurately.
Cell.
Cell. Even Perfect Cell Can beat him. actually if gohan beat cell but it took vegeta to send goku some of his power to beat broly that means that broly is stronger ------------------------------------------------------------ Vegeta is ignorant since then. Cell is still stronger regardless that Vegeta to send Goku some of his power to beat Broly. I said again, Cell wins.
Cell.
you have to fight the first battle in the broly saga goku vs broly
Cell saga 1st movie: Cell Saga 2nd movie: Shortly before the World Tournament Saga 3rd movie: It is unknown.
Super Perfect Cell
No. The introduction of DBZ:Budokai 3 Introduction where it shows Broly vs Gogeta does not count. Broly couldn't beat Gogeta, let alone Cell, as well as any characters around Cell's level.
He doesn't while fighting the first time because that is before the cell he faces Cell. He is already died the second time Broly comes back so Gohan beats him with Goten and Goku but Goku his not really there.
Broly because he can defeat all the z fighters with not a scratch and cell has so much trouble trying to kill goku alone.
No one knows yet how the first cell came about.