Hey Yams - I can help here I run into questions of Parody and Fair Use all the time on the Internet while blogging.
The question of Parody and Fair Use deals with a) an attempt at making fun of an original concept and b) the amount of the original concept used in the parody.
What you can't do is mimic a character in name and likeness and call it parody. I can't draw Batman as Batman and call it Batman.
Mad Magazine (who paved the way for much of parody and fair use law) gets away with this by drawing a good likeness of Batman but calls it Battyman or something.
Likewise I could say 'I'm Batman!' and draw a picture of a vampire bat.
Lastly, I can ape or mimic a certain artist's style just so long as I don't draw their specific characters. I can draw characters in the 'style' of say Calvin and Hobbes or Adventuretime just so long as I don't draw those specific characters. I could draw an original pony in a MLP style and call it My Little Gothy or My Big Ass Pony and be fine.
That's how parody and fair use work.
Let's look at this then: You have created a piece obviously inspired by MLP - but you have not drawn them in likeness, name, or style. It mirrors MLP but does not infringe - even if you used the same color scheme. The most I would do is call it 'Your Little Llamas' or something, but I don't think you even have to do that.
The people who are in real danger if anyone decided to do anything about it are Artist's Alley prints. I can't draw Batman in my own style and sell it under the pretense that I am selling a picture of Batman - especially the closer and closer it looks to the actual concept. All those people who draw Doctor Who and comic portraits and characters and sell them as such walk a very grey line.
They are selling a licensed character as a licensed character even it is done in say Disney style. That is not parody - that is 'Fan Art' and it is a very large can o worms.
Well this SHOULDN'T fall under copyright issues because it is all originally created design and names. But I am not a lawyer or copyright consultant. DA has a DMCA section you could ask, I do not rem how one asks but there was a DA news thing on it once.
Could change Twili to Twillama. Nerfs the name even more from original.
Thanks, to be honest I've seen total ripoffs of Rainbow Dash being sold on zazzle only her cutie mark and name were different, so I don't think this would be a problem, but I figured I would ask. For zazzle I'd probably just color them and leave the names out, although they are pretty funny.