>>46950362Play Colosseum if you want a more challenging experience that nudges you toward using a lot of Pokémon you've probably never used before. Bosses can actually be somewhat difficult due to their frequent use of weather combos or debilitating status effects. Colosseum also has pretty good atmosphere.
Play Gale of Darkness for a more laid-back experience. The game isn't as challenging as Colosseum but added a few fun mechanics like wild Pokémon and the purify chamber to make purification more convenient, which in turn makes it easier to use a variety of Pokémon. The atmosphere is a little more lighthearted but in a way that feels pretty cozy.
I like to replay both of them now and then because they're both good but I lean a little more towards Gale of Darkness. I think it's just a little more polished and the variety of Shadow Pokémon plus the ease of actually purifying them gives you a bit more freedom in what you want to use compared to Colosseum
