Where do you get a lot of red shards in Pokemon Black 2?

In Pokémon Black 2, you can obtain a lot of red shards by fishing or using the move Surf in certain areas. Notably, using the fishing method at spots like Route 12 or the eastern area of the Pokémon World Tournament can yield red shards. Additionally, you can also find them in the Hidden Grottoes scattered throughout the game. Lastly, you can trade items with certain NPCs in the game to acquire more shards.