Not all legendary pokemon have some hack powers or awesome movesets that why some of them aren't as high in in tier as other legendary pokemon. Manaphy has has sweet abilities, and you can create a great moveset out of it's somewhat decent movepool which is a good His movepool is somewhat limited compared to his fellow Ubers, but what he has is just enough to make him a decent threat.

Manaphy annoys me.

Manaphy is a very good pokemon, so I think it'd be right as uber.

sounds like something from Smogon.com

Who care?

I don't go to smogon.com that site tends to be full with elitist and they think that they are the gods of the pokemon community.

Depends. Are you are casual Pokemon collector, or a expert competative Pokemon Battler?