You are Getting Sleepy...
i've discovered that Pikachu can actually fall asleep when outside of battle and walking behind u. go to the Pewter City Pokémon Center and talk to the Jiggly Puff. it will sing and Pikachu will fall asleep. if u walk away from Pikachu, it wont follow u anymore. when u talk to it, u'll wake it up. if u leave the Pokémon Center when it is asleep, Pikachu will wake up and follow u outside.
Make Pikachu Happy
heal at a Pokémon Center. afterwards, use lots of hyper potions and revives on Pikachu. it wont work, but Pikachu will be super happy. use this to get Bulbasaur.
find a ledge and jump down, but leave Pikachu on top. after a while, Pikachu will start to dance.
before getting Pikachu, press 'A' and 'B' together all along the left side of Pallet Town. go into the grass. u'll run into a Pokémon called Raiblue.
Change Pikachu's Color
change Pikachu's name to "PIKACHAN" at the name rater. Pikachu will have a greenish color.
while Pikachu's dancing, walk straight ahead and Pikachu will slide behind u instead of walking.
use any rod and fish somewhere. then, talk to Pikachu. Pikachu will have a bucket on its head.
go to the trade center in any Pokémon Center. make sure one game has a sucky Pokémon and the other has the Pokémon to be cloned. when trading, it will say "waiting...". turn off the game with the good Pokémon. the other game may now be turned off too. if this is done correctly, u'll both have the good Pokémon.
Glitched Fushcia City
go to the Safari Zone. after u get in, go out. say "no" when he asks if u want to leave. u'll be back in the Safari Zone. walk to the 1st rest area and talk to the man with the glasses. exit the Safari Zone again. say "no" again. when u get back in, save and turn off ur game. turn it back on and try to the exit the Safari Zone. this time, he'll ask u if u want to join the hunt. say "no" and walk out. after 500 steps, they will call u on the PA. u'll be back at the Safari Zone entrance now. walk out to discover a glitched Fushcia City.
enter the Pokémon hotel in Celadon City. go to where a regular PC would be in a Pokémon Center. stand in that place and press 'A'. a PC will turn on.
A House Visitor
stand in back of the girl who's always beside ur house. she'll go into ur house if u do.