Year 0 (Birth): Doomsday and Scorpion
Year 1: Scarecrow, He is a master physcologist and master at chemistry and Geras, he is resureccted after every death, more resilient against what he died to
Year 2: Subzero, Great Martial Arts and Power Of Ice and Raiden, Lightning God (Both are in Injustice 2 and Mortal Kombat 11) Both are very self explanatory