This is one of the few movies I saw on one of my relative's computer screen when I was little. As I was too young to understand anything, it was approximately 15 to 20 years ago (I believe the movie couldn't have come out after 2000, but the quality of the pictures looked good enough that I have my doubts).
The movie I am looking for was fully animated. Potentially a Japanese animated movie, but I can't tell for sure, as I was too young to tell the difference between Japanese, English or any language. There may be blood in the movie, but I can't tell for sure. However, now that I'm looking back, the drawing style looked slightly Japanese, although it was more of the bloody kind (I could slightly compare its style to "Blood: The Last Vampire" (2000)). Maybe it had an Asian tone to it (e.g. it could be a Korean animated movie too).
One of the "bad guys" was a tall, heavy guy, in a very armoured suit. I can't tell whether he was wearing a suit, or if his body was enhanced because he survived an accident (although I have some form of memory about the latter). Most of his body was covered, but I remember his face not being covered. The most distinctive feature he had was the fact that he had a Minigun where one of his arm should be (a bit like Barret in Final Fantasy 7). I think the first time we see him, he's seen crushing a metallic ashtray with his other hand.
A battle scene in the movie includes the heavy guy having a shoot-out against a relatively thin guy (or should I say "normal-sized man"), fighting him with a machine-gun mounted vehicle (he wasn't the one driving; he was shooting from the back of the vehicle). While they were shooting at each others, I remember the heavy guy screaming (nothing in particular, he was just shouting continuous "AAAHH~!!" in pure rage). The fight didn't seem to happen in a city. It slightly looked like a battlefield. The fight ended with some form of explosion, probably killing off the heavy armoured guy.
The other noticable character was a young boy. He looked... pale, almost weird. His skin was almost green, otherwise he looked like a regular child. He seemed to have some psychic powers too: at some point, when he was feeling uneasy and sweating, a man picked a sample of blood from the back of his neck, using a portable device. But when the man was... either incapacitated or down, that boy broke the device containing his blood simply by looking at it.
At some point near the end of the movie, the pale looking boy and some people (with scientists among them) seemed to be inside a huge facility or underground hangar. There was a lot of space, although I can't remember if it was a factory, or if it was an underground weapon storage. The child was also giving some form of speech too, as all the lights turned on suddenly. The others were possibly surprised by what they were seeing.
One last detail I remember about that child is his smile. While it wasn't as scary as the Joker's, his grin was... kind of creepy, because of how he looked at the others with his small round eyes. He was oftenly grinning.
Overall, most of the scenes I remember were quite dark (mostly because there was little light, or it was night time). The two exception being the battle scene (although it was dark, there was a lot of muzzle fire), and the last underground scene with the boy.
When I asked my relative about the movie, all they could tell me was: "The coloured word 'Aiko' was written on the cover of the CD".