Pocket Monsters FireRed

When you use an item on one of your Pokemon outside of a battle, such as a Potion, the Pokemon will either move closer or away from you in the short intermission sequence. How far the Pokemon moves depends on how much it likes you. If it does not move at all, it feels neutral.

To get the diploma, catch all 386 pokemon (i.e. fill the national dex).

Once you have beaten the Elite 4 and have more then 60 pokemon in the pokedex, go to Pallet Town and see the Professor. He gives you and Gary the National Dex, which allows you to view the entries of all 386 pokemon.

Enter the Saffron City Gym, and step onto the warp panel. Now, go:
North, South, South, North, South, North, North, South, South, North, North, North, South, South. You will now be in Sabrina's room, without having to fight any battles.