Dear, it’s not DarkShy

Your color scheme here is incredibly depressing, to say the least. There’s too much desaturation going on.  
Here’s some ideas! Please take a moment to look at them and take them into consideration.
 
-Sweet Apple could probably use a touch more orange in her body and a slightly deeper pink in her mane. As she is now, the two colors blend together and it makes her look very flat.  
-Star Dash’s original colors were great, tbh. If you keep the body color, and cut the rainbow in half (in other words, only keep three or four of the mane colors), I think she’d look fantastic.  
-Magic Spike (may I suggest a new name as well? Perhaps Dawnscale) has alright colors overall, but maybe try a light green (think Spike’s belly) instead of the dark green? Also, keep the semi-dragon tail, or maybe even make it like Darkshy’s tail! ♥  
-Melody Crystal would look lovely if you kept the streak. Maybe try a blue-ish color? I think the streak suits the design very well.  
-Happy Balloon looks wonderful as-is, no suggestions here. :) ♥  
-Darkshy also looks fantastic, though I personally think his tail should be a similar color to his mane (lighter version, maybe?), with a different color for the scales, to make him unique from his father.  
-Thunder Apple’s mane looks fantastic with the two shades of blue. I’d suggest the same light blue in place of the light green, and the same medium blue in place of the dark green.  
-Lastly, Apple Shine’s original design looked perfect. If you really wanted to change something, I’d say maybe put the purple streak from the new design somewhere in her mane?
 
If it helps, I’d be more than happy to make visual examples of what I’m talking about. :) ♥♥  
Those are all just my opinions, though. Consider em, sleep on it. If ya don’t like any one of my suggestions, you don’t gotta follow it.  
At the end of the day, they’re your OCs, nobody can force you to keep or change designs.

There is a concerning amount of grey and green in those manes. I don’t mean to sound like Rarity, but it’s not a good look.