I really like the concept behind these trio—how they bring balance to the Pokémon world by keeping the power of knowledge, emotion, and willpower in check. Their designs are pretty simplistic, which I love. They do look quite similar to each other, but I'm all right with that.
My favorite of the lake guardians would have to be Azelf. Its primary color is blue, and I'm a big fan of that. :) When it comes to battling, this Pokémon can perform quite awesomely. It's got a great Speed stat, which gives it a chance to outrun many Pokémon in its tier and land the first hit. With its above-average Special Attack, it could take down your opponent's entire team single-handedly after just one Nasty Plot. Azelf can learn Stealth Rock, which would make it a great lead. After you have Stealth Rock set up, your opponent's Pokémon would wreck into them as soon as they're sent out on the field, making it easy for you to finish them off. This Pokémon also has access to Reflect and Light Screen. Give it a Light Clay, and it would make an excellent dual-screener for just about any of your team!