You don't have to battle Mespirit you just need to see it in the cave.
To get the National dex you need to see all 150 Sinoh Pokemon then go see the professor.
as for the poke app, he means the Pokemon will show up on the marking map (not the berry one) though you will need to wait a few seconds for it to show up.
If you're missing any Pokemon tell me what numbers they are and I can help you find them.
Why is Manaphy included as 151 in the Sin. Dex? He isn't needed to get the Nat. Dex.
Milestone Post:
2700
[Edited by bes4360, 1/13/2009 2:27:19 PM]