altaria
Pokemon Contests were not "invented" yet.
groudon
treecko
Unfortunately there are absolutely no Pokemon contests in Heart Gold aside from the PokeAthalon.
It depends on what you like. Every Pokemon is different.
there are no contests just a pokeathalon
yes
pelipper
Let's see... Verdanturf Town has normal Pokemon contests. Fallarbor Town has super Pokemon contests. Slateport City has the hyper Pokemon contests Lilycove City has the master Pokemon contests. Also, if you can wait, I'd recommend only making pokeblocks with the people at the master contest hall. You get better quality pokeblocks that way. Good luck!
Pokemon mysery dungeon 2 and Pokemon pearl-diamond
Pokémon Contests are a type of competition often contrasted with Pokémon battles and held in Contest Halls. Pokémon are judged on their condition and moves in two rounds, to determine which is the best of its category. -from Bulbapedia, the community-driven Pokemon encyclopedia
That's a matter of opinion(myne is Giratina)