* The main plot point is resolved: The lakes are primarily a location to catch Uxie, Mesprit, and Azelf, the Lake Guardians. Once you've caught them, the main story element related to the lakes is over.
* No other trainers: There aren't any trainers to challenge or items to collect at the lakes after the Legendary encounters.
* Limited wild Pokemon: The available wild Pokemon are mostly common and low-level, not worth the trip for experienced trainers.
However, there are a few things you can still do at the lakes after you catch the Legendaries:
* Training: You can still use the lakes for training if you need to level up your Pokemon. There are a variety of Pokemon at different levels to fight.
* Fishing: If you're a fishing enthusiast, you can catch some rare fish at the lakes.
* Catching rare Pokemon: While not as common, some rare Pokemon may still spawn at the lakes, such as Gible or Buizel.
* Relaxation: The lakes are a beautiful and peaceful place to just wander around and appreciate the scenery.
Overall, the lakes are primarily a plot-driven location in Pokemon Pearl. While there's not much to do after catching the Legendaries, you can still find ways to enjoy your time there.