These are all very good for someone new. You show a lot of promise. The part choices make sense and blend well. There are no big problems with color saturation. The sticker and pattern use is smart and not overdone.
There are couple of specific things I especially liked. Batsu's headgear, composed of the mask and one of Astaroth's old helmet, is a very interesting construction and goes a long way in conveying the character. I also like the sticker use on Talos' vest. That was a good way of adding some unique designs.
One thing I think you should work on is variation in color scheme for each character. I get that you decide on a color scheme for each character, but there's a point where if you use too much of one color, they start to look color-coded, like they're different members of a Power Rangers-type squad. I think Sion and Talos are your best colored, here. Krieger and Batsu look appropriately colored, too, while Mirai Ichi is just okay and Amelie looks like that's all that's needed.
All things considered, though, your work is definitely worth a look and I think you'll come up with even better stuff over time. I'll definitely be watching for new stuff to come in. Keep it up.
Talos
Utada
Phirus
Edward
Batsu
