Route 45

Route 45, Johto (from Pokemon SoulSilver).

Levels are this area's own. In your first region they stay as shown; in a region you open later they are raised to match your progress, unless you started that region fresh. See levels.

Wild Pokemon

Grass and caves
Pokemon	Levels	Chance
Graveler	23 to 25	55%
Geodude	23	30%
Teddiursa	20	10%
Skarmory	27	5%

Surfing
Pokemon	Levels	Chance
Magikarp	2 to 25	100%

Fishing, Old Rod
Pokemon	Levels	Chance
Magikarp	10	85%
Poliwag	10	15%

Fishing, Good Rod
Pokemon	Levels	Chance
Poliwag	20	60%
Magikarp	20	40%

Fishing, Super Rod
Pokemon	Levels	Chance
Poliwag	40	80%
Magikarp	40	20%

Swarm (grass): Swablu. After the National Pokedex, one swarm happens somewhere in the region each day; on a swarm day these replace the most common slots.
Headbutt trees: Common trees: Spearow (Lv 23 to 24), Heracross (Lv 23 to 24), Aipom (Lv 23 to 24). Rare trees: Spearow (Lv 26 to 27), Aipom (Lv 26 to 27). Which trees are common or rare depends on your Trainer ID.

Items

On the ground (item balls)

Elixir
Full Heal
Max Potion
Nugget
Revive

Hidden (use the Itemfinder or press A on the spot)

PP Max
PP Up