Which Legendary Pokemon disappoints you in terms of:
1) Design
Regigigas. I mean, look at him. Compared to the original Regi trio, this master epicly sucks. Registeel is so elegant, Regirock is so cool, and Regice is so beautiful, but Regigigas is just plain ugly. I mean, being the trio master of three cool Pokemon, Regigigas could at least match them in terms of design, but no. He got a very horrible design.
2) Storyline
Hmmm... Hard to say. I think the three weather genies plot is way too stretched. I mean, there is absolutely no plot behind them, just some random dudes who come up, deciding to mess with the weather and all.funny in Hoenn, they fuss a lot about the weather, and it is just sunny and rainy, whereas in Unova, it is a terrible thunderstorm and yet nobody seems to give a thought about it.
3) Power/Strength
Strength? I have to agree with Cosmotone again. Phione is a lesser Manaphy clone, which is an absolutely lame excuse for a legendary. Yes, they are the guardians of the seas and such, but shouldn't they be more powerful and all? Kyogre is more fitting for the title.