Pokemon: Everything In The Johto Region Changed In HeartGold & SoulSilver

Johto changed a lot from Gen II to IV. These are the most notable found in the remake.

Pokemon HeartGold and SoulSilver :: Full Walkthrough

Pokémon HeartGold Version, Nintendo DS, Games

Pokémon Heart Gold/Soul Silver remakes are a thing of beauty

Review: Pokemon HeartGold / SoulSilver – Destructoid

HeartGold and SoulSilver by Inc. Staff Pokemon USA and Prima Games Staff (2010, Trade Paperback) for sale online

Johto - Bulbapedia, the community-driven Pokémon encyclopedia

Pokémon Gold & Silver vs. Pokémon HeartGold & SoulSilver: Full Comparison - Cheat Code Central

Pokémon Heart Gold & Super Mario Galaxy Collide In Surprising Johto Mod

Retrospective: Pokémon HeartGold and SoulSilver