The connection between his leg and his foot when his right leg is forward isn't very readable. Otherwise, you have made a very common mistake. When you walk, and you put your left arm forward, your right leg goes forward. Here, Mario puts his right leg AND his right arm forward, when it the side of the leg and the arm should be opposite, so it should be left leg and right arm, right arm and left leg, repeat. A plausible and smooth animation, should these errors be amended.
One more thing, it seems that when he turns his body towards us, his shirt does not show, which is unnatural, perspective-wise.
EDIT: His leg looks kind of like it's bulging out of the bottom when his right leg(our left) is back, I'd move the outline a bit higher.
One more thing, it seems that when he turns his body towards us, his shirt does not show, which is unnatural, perspective-wise.
EDIT: His leg looks kind of like it's bulging out of the bottom when his right leg(our left) is back, I'd move the outline a bit higher.