diagla charizard lucario palkia mew and monferno
A lv:100 venusuar!!
There is no best Pokemon.All Pokemon are weak and strong against others.
Have a good Fire and/or Ground Type...
victory road
weedle, sparrow, geodude, nosapass, skitty
Venusaur,Rapidash,Gyarados,Pikachu,Pidgeot and Dragonite
You need a grass type, a fire type, a water type, an ice type, your legendary and a ghost or dark pokemon.
NOT ACTION REPLAY!!! I say elite 4 and if you're leveling up weak pkmn, give'em an exp.share and put your strongest Pokemon in slot 1 of your party.
Fire and water are the best combination to beat the elite 4.
Lugia because it is physic and super affective against poison and fighting but don't use it against dark because they will kill it easily
Diamond is not a Pokemon but i think Arceus is one of the strongest Pokemon ever.
The best thing to do is to continue to go through the elite 4 and give that Pokemon the exp. share.