The Yellow Forest route on the Pokewalker? Pikachu. Only Pikachu.
It is in Ilex forest.
In Pokemon Heartgold or gold and soulsilver or silver you can find it in viridian forest.
Get it in Ilex forest, and it evolves at level 35.
You can find an oddish in the Ilex Forest, only at night though.
you can find a pineco in ilex forest using headbutts in trees.
On Pokemon Heart Gold or Soul Silver you must walk with the Poke-walker enough to unlock the Yellow Forest. If you walk in the Yellow Forest and look for Pokemon it is most likely you will find a Pickachu
you can't .. you can trade it from red, blue, yellow
Pokemon Red/Blue: Viridian Forest, Power Plant (RARE) Pokemon Yellow: Professer Oak gives it to you as your Starter Pokemon (ONLY 1) Pokemon Gold/Silver/Crystal: Route 2 (FEW) Pokemon Ruby/Sapphire/Emerald: Safari Zone, South-West and South-East sections (RARE) Pokemon FireRed/LeafGreen: Viridian Forest and PowerPlant (RARE) Pokemon Diamond/Pearl/Platinum: Trophy Garden (RARE) Pokemon HeartGold/SoulSilver: Viridian Forest (RARE) Pokewalker: Resort, Yellow Forest, Rally, Sightseeing
You can't. You must trade it from Red, Blue or Yellow.
ilex forest shrine
I know in Soul Silver your can only get him in the Viridian Forest . Pretty sure it is the same for Heart Gold
You can't get it.