Games: Heart Gold / Soul Silver (Generation 4)
New ribbons: 1
Total ribbons: 66
How to Obtain:
Defeat Red at Mt. Silver.
This is the HG/SS version of a champion ribbon, it's likely going to be the hardest of these types of ribbons you will have to do, however with a fully levelled team it still should be pretty easy.
Effort Ribbon
You can get this ribbon in Blackthorn City when you show a Pokémon with maxed EV's.
Daily Ribbons (7)
You can get these ribbons from the Week Siblings every day of the week.
Battle Tower Ribbons (6)
You can get these ribbons from the Battle Tower near Olivine City, refer to the entry in the Sinnoh page for more details.
A note about Unova
There are no new ribbons to obtain in Unova, you will however still need to transfer your Pokémon through the gen 5 games in order to continue into Kalos.