If by last Pokemon you mean the last one in the pokedex then that'd be Arceus, #493
Palkia, the one on the cover of Pearl.
Here is a list of all 150 Pokemon: http://www.serebii.net/diamondpearl/shinoudex.shtml The last Pokemon listed (#151) is not required to get the national pokedex.
yes arcaeus is the last Pokemon in the pokedex
Arceus.
Arceus
The last Pokemon in the National Pokedex is number 493, Arceus.
its arceus but I have heard in the newest Japanese pokedex its zaoark
if you meen the national dex then you need to find every Pokemon in the sinnoh pokedex
Garatina...
Mew is the last generation 1 Pokemon in the National Pokedex.
in the national pokedex: arceas in the regular pokedex: dialga