Dialga and palkia.Hope i helped(if u have diamond go celestic town go in longest house and talk lady and left, and for dialga get the master ball from veilstone Galactic HQ)
Pal Park after the two men are out of the way (they should be if you have the national pokedex)
Pokemon Platinum has two different Pokedexes: the Sinnoh dex and the National Pokedex. In the Sinnoh dex, #152 is Rotom. In the National Pokedex, it's Chikorita.
The Pokemon that is number two in the National Pokedex is ivysaur.
well for the normal one Cynthia (sinnoh region champ) had two pokempon i needed to see and i think that's how you see every Pokemon but if that does not work try evolving Pokemon
you could look for it but is too hard, so you have to see all the Pokemon in your pokedex so you could upgrade to a national pokedex then go to the professor he should let you pick one Pokemon from the johto region it should be the first of meganium "chikorita" and two other Pokemon.
you have two transport it from Pokemon ranger. if you just want it on your pokedex then go to bucklots mansion. go to his room and you will see a book on the desk. read it and it will show you a photo of manaphy. then it will be on your pokedex. you can also trade it from Pokemon heart gold or Pokemon soul silver,or mystery gift.
You have to buy two games and two Game Boys and a link cable and trade in between the games
You have to see every single Pokemon on your pokedex. So look in your pokedex, and if you see a ? in a spot where a Pokemon should be, then try to find that Pokemon. (when i first played this game, I had this same problem, because i never saw Uxie, the being of intellegence. Go to all three lakes and catch or defeat the Pokemon there, because this is most likely your problem.)
493 is only how many the pokedex says there are. But Pokemon like shellos there is two types but the pokedex only counts it as one. Arceus evolves into different types if you use a certain type of stone and the pokedex still only counts all those combinations as one. If you want to see it for yourself check out this website: http://www.serebii.net/diamondpearl/newpokes.shtml
You go to the Pokemon mansion and the first door on the right go in talk to the two men then behind them there is a book and if you read that then you get manaphy added to the pokedex
There are only two Pokemon(without the National Pokedex).They are Pickachu (into Raichu) and Eevee (into Jolteon).
You can complete the pokedex on Pokemon Blue version by trading with you friend who has Pokemon Red version. Or you could do what I do and get two gameboy color's and multiple Pokemon games because none of my friends play Pokemon anyomore; even though it is one of the best games of all time =).