Pokémon Gold and Silver/Route 30-31

'Route #30 and Route #31 are relatively uncomplicated roads—unfortunately, you'll have to wander off the path to climb uphill. You'll be wandering through tall grass again, but it will help your Pokémon become strong—if you win.'

Trainer Battles Begin
When you return to Route #30 after completing your errand, trainers will attack you whenever you make eye contact. As you can see from their rosters (to the right), their Pokémon are weak, but they can wear you down. You can try to avoid them, but it's better to fight when you can: they're the best source of money and EXP in the game.

One new twist is the ability to trade phone numbers with certain trainers once you've defeated them in battle (they will say phone next to their rewards). If you agree, they'll call you periodically to chat, challenge you to rematches, and most importantly, inform you of Pokémon "swarms." Without that info, it's hard to catch Pokémon like in the nearby Dark Cave. A few, like Wade on Route #31, will even give you free items!

Free berries from Wade
After you beat Wade, give him your phone number. He'll call from time to time, and if you go visit him immediately afterward, he may give you one of a wide variety of Berries.

Catch a Bellsprout (or Two)
The dividing line between Route #30 and Route #31 is right about where the trainer named Don waits. To the north of him you'll find pretty much the same Pokémon you found below, but with the addition of and. Try to catch an extra Bellsprout—not because they're that great, but because they can be used to trade for a very useful in Violet City.

Run an errand and get TM 50
A little later in the game, a guard in the guard house that separates Goldenrod City and Route #35 will send you to deliver a message to the guy in front of the lake, so remember where he's at! Finishing this errand is the only way to get TM 50, Nightmare.