Name: Pokemon Master Quest Johto
Remade from: Pokemon Soul Silver
Remade by: Leaky Lou
Source - Credit about Pokemon Master Quest Johto: pokecommunity.com/showthread.php?t=406739
This is similar to your typical sideshow hack, except it only covers the Pokemon available in the regional Pokedex. For Johto, this means that it's a 256 hack. Leaky Loe has removed all instances of Hoenn/Sinnoh Pokemon, except the 5 that are including in the Regional Dex (Yanmega, Tangrowth, Mamoswine, Lickilicky, and Ambipom). That being said, He has increased the diversity of the game quite a lot. He has hand-edited each of the Routes, Trainer Rosters, and Level-Up Sets. He couldn't edit the TMs or make them infinite, so instead He made them obsolete. The level-up sets contain pretty much every move you could possibly ask for.
Changed every Route's Wild Encounters
Changed all Trainer Rosters
Changed all Pokemon movesets, as well as many abilities and stats
Max Trainer AI for all trainers
All 256 Pokemon Available to catch ingame (almost all in the Wild)
Kris instead of Lyra, GB Player from start (thanks to HGSS Golden Edition)
Check out the documentation for more in-depth info
You can use evolutions of Pokemon other than the Johto 256, but they aren't supported and thus won't learn any new moves and haven't been changed by the game. Most of their pre-evolutions stats have been boosted anyway, but if you really want to use them, Leaky Lou recommend waiting until you have a moveset you're comfortable with or level 50 when a lot of Pokemon stop learning moves. Evolutionary items like Magmarizer and Electrizer are available in the game pre-E4 because he used the HGSS Golden Edition as a rombase for this.
Documentations for this game:
Pokemon Master Quest Johto Document
Download Pokemon Master Quest Johto Completed