Well, if you look at Gen V Ubers, it's 1 Gen I (Mewtwo), 2 Gen II (Lugia/Ho-Oh), 5-8 Gen III (Kyogre/Groudon/Rayquaza/Blaziken/Deoxys (3 alt formes)), 7-24 Gen IV (Dialga/Palkia/Giratina (1 alt form)/Manaphy/Arceus (16 alt formes)/Shaymin-S/Darkrai), and 7 Gen V (Excadrill/Genesect/Reshiram/Zekrom/Kyurem-W/Tornadus-T/Thundurus).
So, ignoring formes (Species Clause calls them the same Pokemon), Gen IV and Gen V are tied. However, power creep is clear: Pokemon in here on the merit of their own performance alone (no abilities necessary) are Mewtwo, Ho-Oh and POSSIBLY Lugia, Deoxys, ALL of the Gen IV except for Manaphy and the Arceus formes, Reshiram, Zekrom, Kyurem-W, Tornadus-T, and Thundurus.
That's four from the first three generation and ten (or eleven depending on if you count Normal Arceus) from the other two. Power creep is very visible.
nuskooI posted... You nooblet mainstreamers and your reverse nostalgia.