I almost always let them evolve, often for my Pokedex, but also because the stats are higher. Even if I don't like an evolution at first, I usually learn to love it (such is my case with Walrein and Wailord).
I use my Eevees' personalities to decide their evolution, in those specific cases. The only Pokemon I don't really ever evolve is Dragonair, because I don't care for Dragonite all that much. If I get a second Dragonair, I might choose to have it evolve. But not the one I actually use in battles.

Hi everyone! I've been signed up for awhile but I finally rechecked the site and with the game seeming to come out soon I hope to be a bit more active.

I've been a fan of Pokemon since I was little because of the show, and the first Pokemon game I ever played was Crystal version (my friend's). The first game I played through/owned was Pokemon Sapphire. I also own Emerald, Yellow, own(ed) Diamond (went MIA), and now have White. (So if you want my friend code, just ask! I really want to trade, especially with Black, 'cause my Unova Dex is almost full!)

As for my Pokemon preferences, I like pretty Pokemon that can seriously pack a punch, and a balanced team. I prefer Psychic, Water, and Fire types, but that's not all you'll see on my team, believe me.
Musharna/Munna and Espeon are especially beautiful! I also like Dragonair, Lapras, Kangaskhan, Torterra, Samurott, Simisear, Typhlosion, Wailord, Blaziken (I had a pair of Blaziken and Wailord that could kick anyone's butt at one point), and all three original starters. Gurrdurr is really one of my few exceptions to the rule of "beauty and power," because he's really not that nice-looking at all, but Mr. Handyman is really handy, especially in a pinch, in my White version!

If Pokemon were real, I would start out in the Johto region with Cyndaquil and an Eevee (which, of course, would become an Espeon).
My goal is to be strong, but I would rather own a Pokemon Daycare and be a Breeder rather than a Champion.

Also, I nickname 99% of the Pokemon I catch because it's fun to. And double battles are the best.

Sorry if this is too much text. ^ ^;;