Immediately the idea is better
Why can't we just have a Justice League/Doom Patrol amalgam Earth instead ?
Superman is Robot-Man, the brain of Kal recovered when his rocket didn't protect him from the crash completely
Diana the Island
Batman/Crazy Jane. CRAZY BAT
Aquatic-Girl. Rita Curry through some Atlantean magic is now made of living water
Negative Lantern. Larry Jordan ? Hal Trainor ? In a 3 way crash, the ace pilot, the negative spirit, and abin surs craft collide creating the Negative Lantern Ring which now holds the spirit, and is what Hal/Larry now uses to cling to life
The Martian Beast Man. Garfield Jones gets a life saving blood transfusion from a dying Martian and is transformed into a animal shapeshifting half Martian creature