Probably the best Pokemon game in the last decade. First off - the graphics are a phenomenal recreation of the original Gen 3 games, while still keeping the feeling of those games intact. The story is MILES better than most recent Pokemon games (I'm looking at you, Sword and Shield), and adds another layer to the already great story from the original Gen 3 games. Now, Gamefreak could've stopped there, and this would still be a solid Pokemon game - but they really went all out. The post-game story is basically everything I ever could've wanted, and is honestly better than having an Emerald remake. The story of the Delta Episode is just as good, if not better, than the story of the main game, and has some really epic moments at the end. That's not all, though. After you beat THAT, there's a MASSIVE endgame with all the different legendary Pokemon you can track down, the player bases (which also have a lot of interesting potential), and the battle mansion, carried over from X and Y, and also having been improved since those games.
Hands DOWN my favorite Pokemon game of all time, and even 6 years later still worth getting.