Well... If I were a Pokemon I'd be an Absol whom which can't evolve and if it could I wouldn't... Unless I could evolve into my fakemon Absoloton but that's unlikly to happen. =p.
It depends which pokemon I was. I have a feeling if I were a pokemon that evolves, I would have evolved long time ago without thinking about it. >_> Like an idiot. Just go.. "Woa, I'm gonna evolve riiight now because I can. *evolves* Lololololollolollolz~!!" Then a few minutes later, I'd totally regret it.
Yeah. I'd be a Growlithe evolving into Arcanine. That way I'd be bigger, stronger, faster, and I could protect my trainer more affectively when he/she sleeps and they can use me as a big, warm, fluffy pillow.