Gen 1: Lacking Wartortle and Bulbasuar AND Ivysaur. (R)
Gen 2: Complete. (C)
Gen 3: Lacking Kyorgre and Mew. (R)
Gen 4: ..... Never played it much so I lack like 40. (D)
Gen 5: Almost there about 15 left. (B)
The only Pokédex I've completed, is the one from Pokémon Ruby, of which the cartridge is almost divided into pieces, but it still works.
I've never completed the other ones, since I started to replace my default Pokémon games since Gen IV.
Got nearly all the Unova ones except the ones that aren't released and Thundurus and Tornadus. I've got all the normal non legendaries though. I completed the Kanto Pokedex, but I must shamefully admit I used the mew glitch method 1 on a copy of Red I borrowed.
Starting with Pokemon Ruby back in 2004, I set out to capture one of every available Pokemon. I successfully did so, only missing Mew, Celebi and Deoxys. I continued this goal with Diamond, only missing the aforementioned three, Darkrai, Shaymin and Arceus.
I never bothered buying either of the fifth generation games.