1) Ironman & War Machine- not an issue for thanos and darkseid
2) Spider-Man, Venom, Carnage & Toxin- might get tricky with the symboits if one of them attackes but i dont think that would work on these two
3) Ultron & Absorbing Man- Omega beams finish off ultron and absorbing man since no science goes behind the effect and if thats a problem then thanos just beats him into a bloody pulp
4) The Fantatic Four-thanos with prep is even smarter then FF and so is darkseid no contest
5) Aquaman & Namor-no contest thanos can take out these two by himself
6) Flash & Zoom-since the Omega beams can traverse time i think they can follow these two if not i still say they win.
7) Wonder Woman, Martian Manhunter, Gladiator, Beta-Ray Bill-the team has to try harder but if darkseid isnt jobbering he finishes them fast
8) Doomsday gets sent to the end of time instead of oblivian
9) Champion (/w Power gem), She-Hulk & Savage Hulk-gets punked like he did the first time he fought thanos and she hulk and savage hulk get erased
10) Captain Marvel, Black Adam, Superman & Thor-ooooo captian marvel and black adam and thor get erased then darkseid and thanos team up on superman and kill him
11) Hal Jordan, Sinestro, Magneto-all of them get erased
12) Silver Surfer, Firelord, Terrax & Fallen One-erased
13) Tyrant-erased
14) Dr. Strange, Dr. Doom & Dr. Fate-erased they cant get rid of darkseid since he is protected by the source so magic wont work and thanos is doom times 100
15) Odin-thanos takes a break and watches odin get beat up by darkseid
16) Sentinal Alan Scott-poor guy i hope he gets erased
17) Asgardian Destroyer-erased or pummeled
18) Galactus (70%)-darkseid stalemates him and thanos goes into his ship and plants a bomb so that big g dies while fighting darkseid
Do they live to tell the tale or die horribly along the way? yes they live big g is the only real threat but darkseid is just as strong if he's not jobbering they could even combine there mental powers and crush him.