I plan to complete the guide so, starting with route 30
Drop rates seem to be abysmally low, I do not recommend farming here.
After 5hrs of picking up I gathered these:
Grass:
Pick-up Ability.
Potion, Antidote, Repel.
Wacan Berry, occa berry, plain seed
PokeBall
Rainbow quills (obvs)
Trainer Pickup:
PokeBall, potion, Lure
Next I will check surfing in Route 30. Will update soon.