Well it would be the same sprite, just edited to look "right". Samus has an outline, for example, that is not present in Metroid. This would be more Xtreme (pardon the pun), but not unprecedented. Iiiiii...derped entirely on that. You're right about his jump. Although Wall Jump would work in some scenarios, there are many where it would fall short of being any kind of helpful. Maybe the mid-air dash would make up for it? A high jump is also viable, but not at all to the extent of Mega Man's.