3rd Gen Your favourite Legendary

[xGal]

Kyogre. I just spammed Sheer Colds at the E-4 (Elixirs either, on my Kyogre) and unlike Groudon's fissure, it also hits Flying types.

 

[SoraTheTruth]

Lugia
Rayquayza
Latios

 

[Rizardon]

Latios, Groundon or Rayquaza such awesome looking legendaries

 

[Sableye~]

Rayquaza and Latias, off the top of my head.
Specifically shiny Rayquaza.

Edit:
@_@
Someone else had the same answer that I did...

 

[mrcoolbro]

My fav. is definitely Groudon because his drought ability combined with solar beam makes him awesome!

 

[sleds]

I guess I'll jump on the band wagon and say Rayquaza. Favorite legendary of all time. He makes the E4 super easy and his design is the best of all!

 

[Altair1]

Rayquaza sure gets mentioned a lot here, as I would have expected haha, it also happens to be my favorite legendary in 3rd Gen. I found it so difficult to catch, but after that, whatever stood in it's way, it finished.

 

[Nomine]

Would it be funny if I said that Rayquaza was my favorite legendary also? His design and cry are just... epic.