Frieza, King Cold and Cooler show up in the current Marvel/DC Universe (to random locations in the same Galaxy as Earth, but no closer than 10 light years to It). How would things go for them?
Frieza's in his first form, and has all of his men from Namek (including the Ginyu Force). Cooler's in his Base and he has his "Armored Squadron". While King Cold has all the fighters he had on Earth. As well as Cui, Raditz, Vegeta & Nappa (Saiyan Saga).
Frieza:
-Zarbon
-Dodoria
-Ginyu Force
-All the fighters he had on Namek.
Cooler:
-Salza
-Doore
-Neiz
King Cold:
-Cui
-Raditz
-Vegeta & Nappa (Saiyan Saga)
-All the fighters he had on Earth.
(Raditz, Nappa & Vegeta have six Saibamen seeds each)
So, how do they do?
Scenario 1: All DBZ, Marvel & DC characters are in Character.
Scenario 2: All DBZ, Marvel & DC characters are Bloodlusted.
EDIT:
Planet Frieza 79 Is transported to Marvel & DC as well so they'll have a base of operations which will be in a solar system like ours (with Planet 79 taking Earth's place, and being the only Planet in that system with life on It).
All three of them will know the location of the Planet
http://dragonball.wikia.com/wiki/Planet_Frieza_79