People purposely misconstrue on both sides smh.
INCREDIBLY GEEKY POST INCOMING.
Assuming:
GOATku and Vegeta get DB,DBZ and DBS feats.
Superman and Flash get post-crisis, N52 and Rebirth feats.
Both series have inconsistent feats, but it's worse with Dragonball since it is one author as opposed to hundreds.
Strength
-Lifting Strength. Flash is the weakest here, a gap between Goku and Vegeta then a solar system sized wide gap between them and Superman. This only really matters for grappling tough.
That was five days continuously without any sunlight and he only had (literally) a single drop of sweat afterwards. This is low end for him, he should be capable of more.
-Striking Strength. Flash is again the weakest here, Superman comes up second capable of shaking the planet with aftershocks of his punches and even destroying them. Goku did the same against Beerus but on a universe wide scale so he tops out here. I'll scale Vegeta to Goku since they are at similar levels of power.
Speed
-Travel Speed: Flash MVP, no one is as fast as him here, speedforce OP. Superman is second he has crossed galaxy sized distances in moments. Goku and Vegeta are hypersonic at best.
-Combat Speed: Much closer but DC has the advantage, Flash and Superman can both increase their own reflexes/perceptions to attosecond speeds, that's important because then they have valuable time to think of and coordinate a plan. Goku and Vegeta should be fast enough to the point this option won't be abused.
Durability.
-Flash is the weakest, Goku and Vegeta second (wildly inconsistent, they can tank ki blasts from people capable of blowing up planets, then get hurt by bullets and lasers, or can't stay near earth's core too long). Superman has the most consistent durability feats, you really need Kryptonite or a red sun to kill the guy bar having the pure strength to do so.
-Stamina.
-Goku and Vegeta get tired, Flash and Superman do not. Ki takes a lot on the body, hence their constant need for senzu beans.
Extra's:
-DBZ are far superior Martial Artists, Superman's brawling style won't do shyt here. He will get clowned in prolonged CQC.
-Heat Vision might cancel out Ki Blasts, otherwise DBZ has the range advantage.
-DC has the superior intellect. Vegeta is a good tactician and Goku is a fighting savant but Superman and Flash are geniuses who's cognitive ability functions at far faster than light speeds. They also have experience fighting varied enemies.
-3/4 combats have true, free flight. Flash frankly can't do much from the ground. However, Sayain pride won't allow them to doubleteam Kal.
-If they fuse, Team DC is fukked.
-All this is rendered moot, if Superman decides to sacrifice Flash and blow up the planet. Sayains can't survive unprotected in space. This isn't likely though.
- This will basically be Goku and Vegeta taking turns fighting Superman. They can't touch Flash. As long as they are under a yellow sun, Clark won't get tired. They need to finish quickly, they can't win a prolonged fight. If they fuse it will be Gogeta, not Vegito who would make this a stomp.
It can go either way, but Flash is a ghost in this fight, bad partner if they keep it in the air. Green Lantern would be better.
If they act in character, DC would win. Goku and Vegeta's pride is a huge disadvantage. If they are smart and work together they will win.