If you truly knew what the Forerunners had and could do, you wouldn't be asking this question. Read this and you'll understand why: https://www.halopedia.org/Forerunner If it's too long of a read, don't worry, I will give you a few examples of their power. 1. At the height of their power, the Forerunner empire spanned almost the entire Milky Way, the only reason it didn't was because they let other species have their own territory. The Forerunners inhabited over 3 million worlds. This gave them an absurd amount of manpower, and their armor could keep Forerunners alive for hundreds of thousands to potentially millions of years. 2. The Forerunner ships are absurdly powerful, both in armaments and hull strength. In the game Halo Wars 2, the Banished attempted to destroy the [i]Spirit of Fire[/i] (this ship https://www.halopedia.org/UNSC_Spirit_of_Fire) by ramming it with a Forerunner ship. The Phoenix logs (in game lore) later revealed that the Forerunner ship in question was a single fighter. For a more powerful example, let's take [i]Mantle's approach[/i] (this ship https://www.halopedia.org/Mantle%27s_Approach), it was not the largest of Forerunner vessels despite being 371 KM tall, but it was the most well armed. While [i]Mantle's Approach[/i] is the only ship of its kind, it gives you a sense of how powerful their ships really were. 3. They could regularly destroy planets and stars without issue, which was a tactic they commonly employed during the Forerunner-Flood war to prevent the spread of the Parasite. 4. They were only capable of being defeated by the Flood. Many, many years before, they had even successfully eradicated their creators, who were known for their capability of creating virtually indestructible constructs. The only reason the Forerunners lost was because of the Flood (and maybe because they put the biggest idiot in all of science fiction in power). 5. When they lost, they made sure their enemies wouldn't win either and just wiped the galaxy clean so that their enemies would never enjoy the spoils of their war. The only negative aspect about their military power was their arrogance, however, they are more than capable of backing that arrogance up. A far more interesting matchup would be the Ecumene vs the Forerunners (whose empire was also known as the Ecumene) considering they almost drove the Hive to extinction, and only lost once Oryx gained the power to take.

If the vex can’t do it, the forerunners probably couldn’t either. They wouldn’t win, but they wouldn’t lose either.

forerunners by far. They have better tech, and if the fallen try to fight back, the forerunners will give them the big f*ck you and use a composer on em.

I mean, the forerunners could just fire the rings and hide out on shield worlds, so...

Fallen. Their bullets track... 🤣

Forerunners........no contest whatsoever. Better war would be Taken King Oryx, Savathun, Xivu Arath, Worm Gods, Taken, and Hive vs Silentium Flood.

Thanos

What makes you think the Fallen should ever be put up against the Forerunners?

Master chief teamed up with Saint-14

Bruh....that's not even a question...Forerunners. They'd beat everything in the Destiny universe except for the Taken. They'd kick the Vex's ass too. Sure the Vex would put up a fight but the Forerunners would win in the long run. They're faaaaaaaaaaaaaaaaar more technologically advanced than the Vex.

EVERYTHING from Halo beats Destiny lol

Forerunners bc fallen have no kell and we have decimated all houses

Flood vs Hive Cabal vs Brutes Covenant vs Fallen Forerunners vs Vex

Well it depends. The Fallen have tenacity and will continue to claw at the walls of the Forerunner cities unless they strike them down. Beneath the ruins of the Cosmodrome, in the shadow of an old colony ship they have located the House of Devils' Lair, and the High Servitor feeding them their strength. They must destroy this machine-god, and send their souls screaming back to hell.

It depends what difficulty are they on.

Not even a competion Even when the forerunners lost against the FLOOD, They STILL got the last laugh! (Halo rings)