Actually, you're one of the many who don't know the definition of 'uber', then. Ubers are precisely what you call 'overpowered godlike ubers'; pokemon with a base stat of over 500 or exceptional movepools and/or traits that make them stand out. Those pokemon are:
Mew
Mewtwo
Wobbuffet
Ho-oh
Lugia
Kyogre
Groudon
Latias
Latios
Rayquaza
Shaymin
Darkrai
Aruseus
Cresselia (I'd still be okay with the use of this one, though, as there are so few walling pokemon that make the cut in D/P)
Heatran
Palkia
Dialga
All legendaries not listed here fall into the OU tier. Also, note that one of the ubers is actually a non-legendary: Wobbuffet. This one is an exception because of the extremely powerful combination of the Shadow Tag trait, its counter attack moves and encore which basically assures that it will either KO whatever it switches into or mess it up so that the next switch-in can do as much. Mew is on the list with a 500 base stat total because of its incredibly wide movepool. Regular legendaries (Regi trio, legendary birds, legendary cats, celebi etc.) aren't disbalancingly powerful because - while many of them excel at something - they all have a very obvious and easily exploitable weakness to balance it out (Bug attacks for Celebi, Rock for the legendary birds, etc.). In other words; the examples you mentioned aren't uber.