mei is a defense character with a freeze ray that can also shoot icicles, build walls of ice and freeze people.
meis opposites are phara, junkrat and reaper. she could kill phara with her icicles and use her walls to stop junkrats grenades, she could also freeze reaper and then quickly finish him with a other shot from her icicles.
junkrat is a defense character, he uses a frag launcher to throw grenades, he also has two traps, a steel bear traps and concussion mines.
junkrats opposites are phara, widowmaker and hanzo.
he could put his traps in high up platforms to try and trap hanzo or widowmaker and stay in well covered areas to avoid phara.
hanzo is a defense character, he uses a bow and arrow to attack his enemy. his secondary attack is a arrow that lets him and his team mates seen through the walls it was shot at, he also have a arrow that fragment to strike multiple targets and his alt he summon a titanic spirit dragon to help clear out the other team.
his opposites are tracer, widowmaker and mei. he could easily defeat them using is alt or his secondary arrow.