No you need ten to be on your first Pokemon then they let you in
10
at least one of your Pokemon need a master rank ribbon from a contest in hearthome
you need ten ribbon to be a Pokemon diamond pearl
If you haven't yet entered the Hall of Fame, you must do that first, then go to the outskirts of Snowpoint City and ride the boat. Make sure you have the National Pokedex(see 150 Pokemon, enter Hall...