Sacred Gold changes base stats, types, and abilities for dozens of Pokemon. Checking the documentation is mandatory. Leverage Typing and Ability Changes
NPCs in Sacred Gold give out high-value items, including TMs and evolution items, that are not in the original games.
: Many Pokémon received substantial buffs. Onix, for instance, has its Attack stat boosted to 80. Review the Sacred Gold Changes PDF on Scribd to see which "trash" Pokémon are now viable. Essential Early-Game Tips