Pokemon Platinum Where To Find Best Pokemon?

It depends what you're planning. Beating gyms? The Pokemon League? Galactic Cyrus? Different tasks sometimes crave different pokemon. Besides, I don't know your favourites. What do you want to train? Any special types?

A good elctric pokemon that is easy to catch and raise is SHINX.  Find it on route 201. It starts out using only tackle but then it gets leer and charge eventually get spark. Its attack is INSANE. It does damage when it evolves into a LUXIO.  It then gets many good moves and becomes stronger. Then it evolves into a LUXRAY. Where it gets moves like Thunder Fang and Crunch. My LUXRAY is a Lv. 49 right now and here´s his stats.
Attack- 150
Defense- 101
Sp. Atk-108
Sp. Def- 89
Speed-81
His attacks are solid, and his special ability is Rivalry, which raises attack if the foe is the same gender.                                                                                                  
-Alex

One of the best pokemon are Dialga  first you have to beat the pokemon League then go to Sandgem town then talk to lucas or Dawn after that you get the lustrous orb and the adamant orb then go to spear Pilar there is a blue diamond there is Dialga.

A magnemite is great. I caught one on the route to Sunnyshore city when it was level 39. I then upped it to level 40. That made it into Magneton. Then upped it to level 41 in Mt Coronet making it a Magnezone. It looks like a spaceship and is very easy to use.

In the rainy area next to veilstone, I found a scyther, it was divine in attack, my grotle[lv27], buizel[lv25] and my BIBAREL[lv22] all fainted I caught it, and i'm not new the world of pokemon.

It really depends on what you all 'The Best.' I have a very strong party which is: Empoleon at Lv 62 and he knows Bubblebeam, Rock Smash, Aqua Jet and Hydro Pump a Staraptor at Lv 62 and he knows Defog, Aerial Ace, Fly and Wing Attack a Lumineon at Lv 61 and knows Water Pulse, Waterfall, Aqua ring and Surf Giratina Lv 62 knows Earth Power, Ancient Power, Dragon Claw and Shadow Force Dialga Lv71 knows Roar of Time, Heal Block, Earth Power and Slash Palkia Lv 71 knows Special Rend, Heal Block, Earth Power and Slash. My party has stayed the same for ages and i am still training intensively!