So let's take into consideration that halo has three Eras the precursor/flood, forerunner, ancient humans, flood, and then the present era each is weaker then the previous. Star Wars has the celestials which can be considered on par with the precursors because not a whole lot is known about either but both had the power to manipulate star systems. Then starwars has the Rakata Which had the star forge, numerous sith empires, armies and fleets, numerous republic armies, fleets. Numerous Jedi armies, numerous lesser known factions that are just as powerfull, Star Wars also has immortals, and force ghosts, not to mention Jedi with battle meditation which can change the tide of any battle. Now these numbers span the galaxy so let's say in this battle as OP said all of each universe. Let's face it the Star Wars universe is far more vast and complex. They would simply overwhelm the halo universe. Although the halo universe wouldn't go down without inflicting heavy losses on the SW universe