it tells you on pokedex go to the map the pokedex says and i think the time has to be night time to show it
You can get them at the lake's. they are lake verity lake valor and something else. mesprit is a roaming pokemon, which means that it roam's around sinnoh, and you can track it's location using the marking map pokeketch app.
in one of the three caves on map two
you find Gastly at night time in the lakes + if Ur to dumb to no than don't play pearl diamond + platinum
You find him like Azelf and Uxie, at their cave except Mesprit will disappear when you talk to him/her(which ever gender you prefer).So don't bother saving your game. To battle him just look at your town map and Mesprit's face will be somewhere. But you should walk there be if you fly his location will change.I found him looking for a different Pokemon find the easiest way is to just look for different Pokemon and hope to find him/her (which ever gender you prefer) randomly.
follow it using your map on the poketech, and weaken it to to 1 hp if you have to, and then throwing a quick ball at it. Or if one of your Pokemon know block or mean look, then you could use that to stop Mesprit from running away. The same strategy works for Cresselia too. But, how will u know where it went?? The map will show a flashing monster icon (Two if you met Cresselia) i still cant find it. which map is it? the berry 1 or the other 1 or is there a different 1? Its the Marking map, not the berry map.
in a map land i know manpey is in map land 8
no
in map 4
on map 1
map 8
in map 6,7,8,9,10,11,12
in any map..........
you find it on map land 8.
you can find a Pidove in map three.
you find it at map 5 or at that place with electric Pokemon
on map 7
u could find him on map 3