Originally Posted by Master Rayquaza
It is near impossible. There is now 649 + 5 Generation VI Pokemon and still counting. I was not into Pokemon back then but, does anyone remember when there was only 150(151). The closest I have ever been to this feat is completing the Hoenn Dex.
impossible, but not impossible.
I was able to complete my National Pokedex on B2 with some hard work and the help of all my carts. Yes, it took a lot of time but I pulled it off. My National Dex is sitting at 648 seen and 648 obtained. I'll finally be able to say that I've completed the whole thing when we get Meloetta.
Now, with that said, it did take time. I had a lot of transferring to do, not to mention the evolving. It was tough but I did it both by regions and by family trees--ie when I got to the Hitmons in Kanto, I sent over a Tyrogue along with the three Hitmons to cover everything. That made things a lot easier.
For those who are wondering, Hoenn was the hardest for me. I had a lot of Hoenn 'Mons stuck on my copy of Emerald which meant I had to Pal Park them then bring them over via Transfer. It was a headache, to be sure but it was worth the effort.