Pokemon Heart Gold Generations

This hack is built using the hg-engine, a Gen 4 upgrade that brings many modern improvements to the HeartGold base.

While Gen 4 hacking is often seen as lagging behind Gen 3, the goal with this project is to show what’s possible and encourage more creators to explore it. HeartGold Generations includes Pokémon from Generations 1 through 9, quality-of-life updates like nature changing, and modern gameplay mechanics, all built into a familiar yet fresh experience.

Features
~950 Pokémon from over 500 families, across all 9 generations are available
All Trade-Evolutions and Cross-Generation Evolutions are available
Infinite Rare Candy & Pocket Heal to help grinding
Portable PC for easy party switching (L Button)
Buyable Nature Mints and Ability Capsules
Type Changes for underused and forgettable Pokemon
Free Heart Scales after 7 Gyms for relearning moves
Free Master Balls after 8 Gyms to help capture Pokemon
Level-Cap in place to prevent overleveling
Fully functional Mega Evolution
Level curve adjusted slightly to make Gym leaders more relevant
Kanto gym leaders as an Endgame boss rush
60fps Unlocked Framerate to speed up your Johto adventure
Gym Leaders have slightly altered teams to promote more Johto Pokémon use
Amount of Pokémon and general difficulty/moveset power are identical (Falkner’s Pidgey to Hoothoot for example)
Some generic late-game trainers have had their levels boosted to be less irrelevant
Three versions of the hack for those who prefer different features

Source: TheGamesDB