Seems like you could stick an Eviolite on Quilladin and hope for the best.Oh man, Chesnaught... =(
I love Chespin, no questions asked. Qualladin gained a little weight, but I still stuck by his side. But Chesnaught... oh God, what did Game Freak do to you, you poor little (big) bastard...
To be honest, it's not the design that's really bothering me, that part is actually ok. It's the COLOR SCHEME!. He goes from almost entirely green/brown, with hints of red on his quills to almost ENTIRELY WHITE with odd bits of green and brown thrown in. It's almost like they didn't even bother to look at what the previous evolution looked like. The color scheme just kills the evolution completely, had they done the colors right it could have been a pretty awesome looking final evolution.
That said, I'll still be going with Chespin as my starter. As awful as his final form looks, I always stick by starter, through thick and horrible final evolutions =|
Chestnaut changed color because plants turn brown over time as they die. It's meant to show he's a veteran, which is also why his fur is a lighter color. I do agree that I'd prefer a more vivid color scheme.