Pokemon: Snorlax, Spearow, Fearow, Raticate, Doduo

Before heading out to R. 16, stop in at the mart, on the rooftop. Buy some sort of drink and keep it. You'll need it later.

West of Celadon is Snorlax and HM02. To get that, chop down the bush and go behind the fence, and through gaurd house. There is a house behind here with a supoosibly famous person in hiding. Talk to her and she gives you HM02.

Now, backtrack to the bush. Head left and you'll see Snorlax. Use the Pokeflute you got from Mr. Fiji. He'll wake up, attack, and you can catch him. He'll disappear regardless if you don't catch him. Don't worry, there is a second one in the world. Contine on left.

If you don't have the bike, simply hold/press the left direction when you pass the guard. You should appear on the other side of him and able to go on Cycling Road.

Straight downhill ride from here. You'll land at the bottom in no time. Continue east to Fuschia.

You'll want to find the Safari Zone. It contains alot of rare Pokemon (Nidoran (F), Nidorina, Nidoran (M), Nidorino, Paras, Parasect, Exeggcute, Venonat, Venomoth, Doduo, Rhyhorn, Chansey, Kangaskhan, Scyther/Pinsir, Tauros, Magikarp, Dratini, Dragonair) and two items you will need for later (Gold Teeth and HM03). You'll need $2000 for this, because most likely you won't find them on the first try. Exlore the S. Zone until you find both.

When you found them, look for the two houses in front on a pond. Enter the left one and talk to the guy in there. If you have Gold Teeth, he gives you HM04. The other house contains a fishing rod.

Find the gym (southwest corner). Inside, there are hidden walls. You'll have to navigate through them to get to Koga. If you were to look at the gym aerially, the path is almost an upside-down U shape. Koga can be hard if you do not know ground, rock, or psychic moves.

Psychic or ground type moves can whip the floor here, but if you don't have them, use hat's best; mainly flying or normal based moves that do alot of damage (Strength, Fly, Mega Punch/Kick).

With Koga down, head over to the Safari Zone and catch a few Pokemon. Then, fly back to Celadon.