Route 15 begins at the cut-able tree. If you use Cut, you can find one trainer at the north-half of the route. Further west is TM20 Rage. This is a physical attack that increases in power each time the user is hit by an attack. The only downside is the fact that once you select it, your Pokemon can’t do anything else until it faints.
Fuchsia City is located to the west. On the second floor of the route house is Professor Oak’s Aide. If you’ve captured 50 different Pokemon, he’ll give you the Exp. All. This item will spread the experience points throughout your team instead of being forced to switch out your Pokemon to earn a bit of experience. It’s a quick way to level up an entire team of low-leveled Pokemon with a single strong Pokemon battling.