They still have some of the best 3D models, animations, and sound effects of any other games.
They still got some of the greatest original soundtracks and remastered R/S/E's battle themes better than ORAS did.
Stories get criticized for "babies first edge in a kids cartoon" but they were fresh air and better than anything most of the mainline games did.
Colosseum's map design was weak but it had some cool shit. The thug city and its neon underground sector/colosseum were pretty great. XD fixed this overall and added some great new areas with more depth.
Stealing shadow Pokemon from their trainers mid match while having to deal with every other Pokemon on the field was a good challenge and something I miss.
Doubles battles as the main format is better than singles, especially when the ai was made to use its own strategies. Colosseum's final boss rush and Dakim (+ having to steal their extremely low capture rate Pokemon) were my favorite fights in any Pokemon game ever, probably the funnest difficulty of any Pokemon game in general. Plenty of memorable fights.
Colosseum had my favorite battle mode of any other game besides maybe the Battle Frontier but its a shame Gale of Darkness shat on it, I was probably the only one that cared for this mode anyways.
Perfect experimentation. Gale of Darkness was the first game to have Evee as the starter and I'd still play that over LGE any day. Groudon and Kyogre being on the cover yet never seen or available in the game as with most of gen 3 being scrapped in favor of a bunch of gen 2 shitmons nobody cared for was a piece of shit move though. (pretty much saying YOU HAVE TO BUY THE ADVANCE GAMES AND THE CABLE TO CONNECT IF YOU WANT TO USE ALL THE COOL NEW POKEMON OR TRANSFER THESE OLD SHITMONS TO YOUR NEW GAME.)
Get Square Enix back in here.
Best Boss Battle
https://www.youtube.com/watch?v=Ui0FURuhXGEBest OST
https://www.youtube.com/watch?v=zZW14zJdp4E 
