The "perfect" Pokemon Yellow romhack alters everything annoying about the classic Gen 1 game while still keeping its best glitches and quirks intact

gamesradar.com:

A team of dedicated Pokemon players has created what they're calling the "perfect Pokemon Yellow romhack," which is full of incredible quality-of-life improvements and tweaks that make replaying the classic first-generation game much more enjoyable. 

Titled Pokemon Yellow Legacy, the project has been led by content creator Patrick 'SmithPlays' Smith, who's also behind the Crystal Legacy project. Yellow is one of the very oldest games in the series, so as you'd imagine, a lot has been changed for the better.

For a start, running shoes have been added so you no longer have to slowly walk around Kanto, your bag has been expanded so you can hold more than 20 different things (seriously, how did we ever deal with this?), and your Pokemon now have visible EXP bars in battle. At the start of the game, you can choose to play as a female character, and the Pokedex has also been given an enormous upgrade, now showing what moves each Pokemon learns.

We're going to have to quickly speed through many of these changes because there really are so many, but Legacy tackles Yellow's awful move variety by rebalancing moves and making certain ones more widely available, and altering the learnsets of Pokemon so they have a better selection of attacks. All Pokemon are now obtainable without trading, and 'mons that'd normally evolve by trade can now evolve simply by reaching certain levels, so you can get your hands on a complete Pokedex. 

Oh, and did I mention that a new Hard Mode has been added? On top of all that, plenty of new content has been added that you can dive into after the credits roll, with Gym Leader rematches, as well as battles with Professor Oak, Nurse Joy, Officer Jenny, and more.

Perhaps the best part about the whole project though is that while it aims to bust a few of Pokemon Yellow's bugs and glitches – like the one that made Psychic types immune to the Ghost types they're supposed to be weak to – the beneficial ones and those that are intrinsic to Yellow's classic