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.
This only works on grass. Once you obtained CUT, you can cut the grass so you won't find any Pokemon.
There are places in the game where important people/Pokemon have stood at one point. If you use the Itemfinder on the EXACT spot where they were, a special item will be found which is usually very rare. You cannot find these items any other way.
In the safari zone , stand in any grassy area. Instead of moving left and right, just tap left or tap right so that your character turns but you dont move. By doing this, you'll still run into random encounters but your time in the safari zone will not decrease.
Go to any Poke Mart and click on the clipboard near the shopkeeper. The clipboard is a questionaire. Type in the 4 words "Link Together With All" and the shopkeeper should notice and gives you access to the Mystery Gift system. Save the game and restart. At the Front Menu, there should be a new option called "Mystery Gift" With Mystery Gift, you can unlock many things.
Go to Island Four and go to the lowest house and talk to the man inside and do the following things: