Route 48

Route 48 is the last route in the Johto region.
Route 48 begins on the east side of the river that runs over the west waterfall on Route 47. Almost immediately, it crosses over the river by way of a bridge, toward the long grass. Various Pokémon can be found in the grass. 
North of the grass, another bridge crosses the river again, and the route ends at the Safari Zone Gate. It has Diglett, Tauros, Gloom, Oddish, Vulpix (rare, only in SoulSilver in morning and afternoon), Farfetch'd (morning and afternoon only), Hoothoot (can only see by using Headbutt), Hoppip, Spinarak (HeartGold only, use Headbutt on a tree), Ledyba (SoulSilver only, use Headbutt on a tree), Pineco, Exeggcute. (These two can only be found by using Headbutt on a tree, and you only have a 20%-30% chance of finding them.) There's also Plusle and Minun (which you can only get using Hoenn Sound, which is only available on Wednesdays), Shinx (only by using Sinnoh Sound, which is available on Thursdays).