Terrragon: Maybe a bit too dithered? Although I do see that your personal style involves a lot of dithering, and third gen sprites (Ruby/Sapphire/Emerald/FireRed/LeafGreen) sometimes use dithering, but too much of it can take away from the "pokemon feel". The backsprite is very nice, and dithering is widely used in backsprites so it fits your style very well.
Carcagon: Its backsprite looks almost like it is facing right directly. Maybe hide the gem from view, since if it would be looking towards the upper right direction, I don't think we'd see the gem. And maybe reposition the "ears" like Titaneon's.
Titaneon (sounds like an eeveelution, lol): This one's my favorite among the three. The pose really works, considering it's very hard to come up with poses for snake-like bodies. Steel/metallic parts are really hard to manage, even I myself can't shade metal properly without using references like Skarmory or the Magnemite-line The face looks over-highlighted, seeing you used a highlight color and added another highlight (white) on top of that highlight color (see attached ok wow terrible example punches self I hope you see what I mean). Also, you might want to reconsider your palette, you can save up to 4-5 colors.
Overall, your fakemon concepts are really creative. You can do backsprites very well, but be careful with dithering for front sprites.
Again, these are all personal opinions and preferences. Keep on spriting, you're very good at it!