in the lake by your house at the begging of the game
Sorry, but no.
Here is a walkthrough on how to catch Mespirit: http://www.youtube.com/watch?v=ee1-2AU0k6w Do exactly what he tells you to do!
You can't catch Mespirit if you killed it, it will mysteriously disappear in the game. It's the same thing as if you defeat a Legendary Pokemon, you won't have another chance to catch it.
Verity lakefront
by searching in the grass
go to acuicity lake
catch them from there lakes then mespirit will run away so maybe use a materball
weaken mespirit a bit and use dusk and quick balls you might be able to use heal balls on it
Emmurrito is a Pokemon that is also known as Mespirit. To catch it, you have to find it roaming around.
after seeing it in the lake cave you have to chase it down and catch it
use hypnosis after taking its hp down
After you've released Uxie, Mespirit and Azelf from Team Galatic HQ, go to Verity Lake. Surf across to the cave. Inside you'll see Mespirit. Talk to it. After it runs away, it will be roaming the Sinnoh.