Judging by the Rival OWs, the skin wasn't defined and shaded properly, as it doesn't have four shades and is bright and un-contrastic, unless you are looking for a person fashioned after Snow White. And his hair looks messy, but I guess the nature of his hair must be messy, but there are two loose pixels hanging at the edges. As for his trainer sprite, his eyes are janky, and not in one level with each other and look small, so it gives the impression that the rival is a forty year old man. I think the hair could use a bit of an uplift, as it has been not frizzed properly either (I've been there, the situation is difficult). The collars look overdone and difficult, and the jacket isn't shaded well. The outlining is bare; and messy at some parts. Also near the waist there seems to be a lack of quality of shading and outlines.
As for the Agent, his OW seems much better although there should be more difference between the black shades; and he has a striking resemblence to an original OW. His sprite, though, looks much like a poorly resized Volkner with different hair and goggles. The outlines are very messy and need proper defining and the pocketed hand seems more like a bunch of clustered pixels. The shoes in particular look distorted. The hair needs to have lesser shade differences, the upper part is very gray and ruins the hair a lot.
Sorry if I shot at a lot of bad qualities, but I think it's more important to correct our mistakes rather than admire the good.
Ok make the trainer sprites later. Do the Ows now and yes, I want this for my hack. Or if you want, you can just edit the nomral trainer sprites(nate and rosa) rather than making the sprites from scratch