Ryu carries a duffle bag full of tidy whiteys
Ryu hits up Ken solely for Laundry
“The master has failed more times than the beginner has even tried.”
-Stephen McCranie
Fighting game Canon tends to be a pain, especially MK and SF. Akuma doesn't really have any major losses in canon. He killed Bison easily and the only people to survive the Raging Demon are both crazy strong in their own right. Then there's splitting Ayers Rock, which comes up a lot.
Current Shao Kahn has been humiliated twice, both by people I would put pretty far below Akuma's level. Liu Kang punched a hole through his chest and despite what some may say, he's not going to tank/ignore that injury. Kitana slashed his eyes and left him blinded and when we first see him in Aftermath, he's getting bullied by grunts. I haven't seen anything that suggests a strength level higher than Akuma.