I dont think i see Dragons Den as a location on the list but i could be bugging regardless..
This is what ive found so far at Dragons Den with lure popped surfing in the water (note: i found the super repel with super rod)
Potions: Super Potion
Repels: Super Repel
Balls: Great Ball, Timer Ball
Berries/Seeds: Haban Berry, Rindo Berry
Other: Dragon Scale, Super Lure
This is what i have found so far on RT 33 in Johto with lure popped
Potions: Potion
Repels: Repel
Balls: Pokeball
Berries/Seeds: Yache Berry, Sucha Berry, Chople Berry, Chilan Berry
Other: Awakening, Antidote, Hard Stone, Everstone,
This is what i found in the grass on RT 43 in Johto with lure popped
Potions:
Repels:
Balls: Great ball, Repeat Ball
Berries/Seeds: Chilan Berry
Other: Silver Powder