Ok, Yoshimitsu is the only Tekken character that changes his outfit/appereance to a completely different one but his face is never shown.
[Here are Yoshimitsus' outfits throughout Tekken: Yoshimitsu Gallery]
I'm just going to point out some of the weird outfits of Yoshimitsu. In Tekken 4 he has fairy/cockroach wings and inhuman and monstrous feet with a rhino helmet and a skull mask. In Tekken 5 he's in full samurai/ninga armour with also a skull mask...and golden crab leg hair or tentacles?? In Tekken 7 he's like...half human and half squid monster. This time he has tentacles for hair, this shares a similarity with his Tekken 5 appereance despite the golden crab hair. His mask looks like a spiders face until the jaw down, which is seemingly to be from a skull.
Today I can't be bothered writing a full page. So to give you an idea of what exactly Yoshimitsu is, I found two Youtube videos about this topic:
Comment please!! What do you think Yoshimitsu is?