Ok, I've finally something interesting about this...
If Yang's attack power after the randomization (which is 0 to 50% additional base attack power which is then divided by 4 since that is how the attack power is derived) is less than the target's defense, the attack misses in the SNES version. In the GBA version, the target always takes 1 damage.
The hit rate is 100% and also ignores evade... and Image and Barrier status.