Or the bombermen in general. But I'll use the white one as an example.
Bomberman is a robot. Robots are typically made out of metal of some sort, at least in fiction.
However, while Bomberman is usually drawn quite shiny, he is also quite colorful. And while metal can of course be painted, plastics may be another answer. That would also be more common in reality (possibly besides industrial robots which aren't meant to look like humanoids). His head also resembles old monitors.

What about his clothes and belt? I have seen seams in a few cases, but usually it's looking solid and as shiny as the rest. Cloth and leather or metal/plastics?

Last but not least: The face. Like mentioned the head resembles a monitor. Does that mean the face is actually displayed? The face is convex and while screens today aren't, they all were back in the 80s when Bomberman came to life. However, I think not, since I can't think of a moment when the face disappeared, despite getting caught in an explosion and the like.
The face is skin colored, but I think it's safe to say it's not organic skin. So that leaves whatever the body is made of most probable?

What do you think?
And how on earth does this all matter? Well it does to me, and I'll explain at a later point.

Technically there are various iterations of Bomberman. From Aliens, Robots or virtual programs.
Also... you are attempting to put logic into a videogame story. Those kinds of things rarely go well in my opinion, but I always seem to do that XD

Now, for the robot Bomberman I don't see any problem in the opinions you stated. I cannot prove in an IRL situation, though. But he is not the only characters to have that kind of attributes in their design. Look at Megaman for example. despite being a robot, there are harrdly any features on his body that make us say "he's a robot", the same deal goes for the "robotic Bomberman". It also depends on the artist.

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http://myanimelist.net/animelist/megatuga

This is something I'd like to write about on my site sometime, though I'd prefer to have a fat stack of evidence and sources to back me up. Until then, here's my way-too-geeky unfounded opinions on the matter!


What the heck is Bomberman?: Some games flat-out say Bomberman is a robot (either built by a friendly scientist, or the creation of a sinister industrial complex)... or they just ignore the subject entirely. They eat, sleep and cry, and otherwise function like an organic being would.
The Jetters anime later on introduces a "Bomb Crystal" at the heart of Planet Bomber, which is the key to "making" Bombermen... as far as I recall. Aside from that, the anime treats the Bombermen like it would any other race, and only a select few characters from the games are treated like stereotypical robots.
But like MegaTuga says, there's a variety of Bomberman types, such as Bomber-Cyborgs, and how they're defined really depends on what game's logic you follow.

Construction: As a cartoon character, it's hard to view Bomberman with traditional robot elements, such as a metal construction and whatnot. I mean, one would assume a metallic construct wouldn't burst when hit by a bomb or grazed by a balloon. =P
My personal theory is that there may be a metallic skeleton inside a Bomberman, but they're mostly made of relatively soft materials... if just to explain their rounded designs, light weight, and why the heck they splatter when fried. I haven't a damn thing to back me up on this one, so make of it what you will.

Face: In Super Bomberman and Neo Bomberman, all Bomberman faces are quite clearly monitors, fizzling into static or blackness whenever they die (except for Rubber Bomberman, who just closes his eyes). Golem Bomber doesn't even have a face, but just an electrical current sizzling on his monitor.
However, those are the only two games to suggest that. More often than not, the faces are closer to a human face - crying, sweating, having their cheeks pinched, and so on.

Clothes: I just see them as what a Bomberman's body looks like. The belt might be optional, but outside of the 4-koma, it's never suggested it's used to hold up their pants or anything.

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