about 75% of the time I do. but only if I can think of a name (for example, when I origionally got my Treeko in Emerald, I didn't name him, since I was out of ideas. However, once I got to Slateport, and Treeko evolved I named him "Phantom" cuz I thought he looked like a Phantom o_O)
All my origionall Starters have Names:
Blaziken= Torcher (Origionally "Torchy" until it evolved into Cumbusken. You know, now that I think about it, "Scorcher" sounds cooler... but I can't change it so... yeah)
Charizard= Charlie (I think I saw another Charmander named Charlie and tought it was cool)
Grovyle (I REFUSE to evolve him!)= Phantom (you know the story)
Blastoise= Squirt (Unamed until I found the Namerater and by then he was fully evolved so.. yeah)
Marshtomp (Can't get past May @_@)= I forget, TBH
Infernape (Origionally Chimchar)= Pyro (another word for fire.)
{Fun fact= Only Charlie and Pyro had thier names from when I first got them. Torcher had a diff name)
Treeko= G Cutter (Gecko, and the move "Cut")
Mudkip= Skipper (*singing*"Skipping through mud!")
Chikorita= CoCo (I forget)
Tododile= Todie (short for Tododile)
Quilliva= QuooQuoo (I forget)
Empoleon= Pippeh (Was origionally a piplup when I got him)
Torterra= Twiggeh (after the episode "Gettin' Twiggy With it!" Origionally was a Tutwig)
Other names:
Swellow (Torcher's partner)= Tal (Probobly short for Taillow)
Swellow (Phantom's Partner)= Kiagee (I don't remember why :p)
Zigzangoon= Ziggy/Zigza/Slavor
Pikachuu= Peaches (lol)
Diglet= Dollie (o_O)
Castform= Idoon (mixed up hungarian for "weather")
Numel= Vollka
Breloom= Shrew (Short for Shroomish)
Omanyte= Ommie
Staraptor (Origionally a Starly)= Staar
Roserade (Origionally a Roselia)= Cosmoe (I think it was after the Sonic X Character)
Shieldon= Shellie/Sheilio
Bulbasaur= Lightarous
Dragonair= HaMinyuu
Lucario= Ria (Origionally a Female Rioluu)
um... I can't remember any other names ATM @_@
~~~~~
Oh, and I can't stand when I get a Non-nicknamed Pokemon @_@
EDIT: I don't nickname Legends though. (Exept Manaphy and Phione)