Pokémon Ruby and Sapphire/Route 123

Items

 * Rare Candy - hidden east of the pier, near the trees
 * TM19 (Giga Drain) - from a girl southwest of the pier, if shown a Grass Pokémon
 * Pecha Berry - soft soil patch west of the pier
 * Rawst Berry - soft soil patch west of the pier
 * Sitrus Berry - soft soil patch west of the pier
 * Hyper Potion - hidden on a rock, east of Hex Maniac Kindra
 * Leppa Berry - soft soil patch on the north side
 * Elixir - on a ledge, northeast of Cooltrainer Wendy
 * Super Repel - hidden in a clearing in a grass patch along the north treeline
 * Calcium - west of the pond
 * Ultra Ball - south of the Berry Master's house
 * Revive - hidden north of the Berry Master's garden
 * Revival Herb (Emerald only) - west of Guitarist Fernando
 * PP Up (Emerald only) - west of Psychic Jacki and Expert Frederick
 * PP Up (Emerald only) - hidden at the end of the middle path of the tree maze in the far east

Pokemon Found
Go down the path. If you have one Grass-Type Pokémon in your party, a girl will give you TM19 (Giga Drain). Grab the Berries here: Pecha, Sitrus, and Rawst, and follow the path to some more Leppa Berries. Then, hop off the ledge to the left to collect an Elixir.

Trainers
As you move to the left, on the low path, collect the Ultra Ball. If taking the high path, grab the Calcium. Either way, you'll end up at the Berry Master's House.

Pillage the nearby Berry Orchard for all kinds of Berries, including Qualot, Grepa, and Pomeg. Once you've looted his fields, go inside and talk to the Berry Master and his wife. The old man will randomly give you two Berries. Come back every day to get a new two. Talk to the Berry Master's wife. She will ask you for good sayings. Concoct a phrase and she will give you a Berry. Once you're done, fly back to Lilycove City.