What is the fondest memory you have of the Gen 1 games or the first Generation of Pokemon in General?
For me, the fondest memory I have of Gen 1 is that overwhelming feeling of completeness and accomplishment I get after registering the Original 151 in my Pokedex. That one moment reminds me of a simpler and happier time in my life where it felt like everything was right in the world.
(Can't say I feel the same now. *sigh* I guess we all have to grow up at some point.)