I have some serious uses for the Promo Smeargle.

1. Blastoise/Exeggutor

Blastoise's power only lets you play a Water energy on a Water Poke. But if you use Smeargle to make Exeggutor a Water type and then get about 20 energy on him...

2. Blastoise/Lanturn

3. Blastoise/Charizard

4. Blastoise/ (Neo 2) Omastar

Ouch. 10 to 40 per turn. Pity there's no way to stop pokes like Dark Hypno or to stop Rainbow.

Unlike 1-4, you can hurt Rain Dance with this guy.

Put Dark energy on a Scyther to do 60 a turn.

The problem with Porygon is that retreating ends the effect, and that you can't change your own team (besides Porygon itself). But if, say, you run R. Zapdos/Sneasel and you're playing against Fire, Smeargle can: (A) make them all Psychic so Sneasel (and Smeargle)resists, (B) make the Fire types Fighting so R.'s Zapdos resists, (C) make R.'s Zapdos a Dark type so it can take out anything, (D) make R.'s Zap Water (it wouldn't work so Sneasel since he'd take 20 each turn) and deal doble damage, or (E) make R's Zapdos Fighting so that he takes nothing from Electroburn!