I would have to say spiritomb because nothing is super effective on it. p.s spritomb is not a legendary,but some people say he is
arceus
a lot of legendary Pokemon
Tornadus
That would have to be Dialga.
there is no best spot
That's a matter of opinion(myne is Giratina)
try serebii.net its got a lotta Pokemon stuff
there are many legendary Pokemon in Pokemon heartgold, but the best is HO-OH
The best Legendary Pokemon with the best stats is none other than Mewtwo.
Dialga in Diamond. Palkia in Pearl. Giritina in Platinum. Zekrom in White and Reshiram in Black.
Best non-legendary water pokemon would be Gyarados. Best legendary water pokemon is Kyogre.
You need a grass type, a fire type, a water type, an ice type, your legendary and a ghost or dark pokemon.