Pokémon: 10 Reasons Diamond, Pearl & Platinum Are Under-Appreciated
9. The Underground
The Underground in Diamond, Pearl, and Platinum was a unique way of building secret bases, getting items, and getting more than one fossil to breed and make competitive Pokémon out of. For so long you could only get one fossil in a Pokémon game. This would make wanting to have a competitive fossil Pokémon incredibly challenging. Unless you had a friend with a trade cable.
In Diamond you could go to The Underground in order to get the hard hitting Cranidos and in Pearl you could get the defensive wall Shieldon. As mentioned before, secret bases were a fun addition to The Underground. In Ruby and Sapphire, the secret base feature was a unique feature that enabled players to have a sense of customization in their game.
Diamond and Pearl added to it and also gave players a small version of "Capture the Flag." All-in-all The Underground was a nice option for players that could have enjoyed it, but if you didn't enjoy it, it was an option that you didn't have to do if it wasn't your cup of tea.