Most, if not all, of these are actually edits...
If you haven't already, please read the pinned "Spriting Encyclopedia" topic. You'll find that custom actually means that you made it completely from scratch, without taking any existing images as a direct base.
If you have read it already... uh...
From comparing them, I'd guess the helicopter is the "most custom" of all these, so I'll give you some crits on it. The way you shaded it makes it look kinda flat, and you probably need a bit more contrast between your shades, so they stand out a little more.
If you haven't already, please read the pinned "Spriting Encyclopedia" topic. You'll find that custom actually means that you made it completely from scratch, without taking any existing images as a direct base.
If you have read it already... uh...
From comparing them, I'd guess the helicopter is the "most custom" of all these, so I'll give you some crits on it. The way you shaded it makes it look kinda flat, and you probably need a bit more contrast between your shades, so they stand out a little more.