Best/Favorite Game? Silver
It was either that or Emerald/Ruby/Sapphire, I chose Silver because it took the original gameplay and expanded it two fold. It was basically two games in one and kept the stories intertwined with each other. Seeing Red and all. I thought that was a really awesome feature.
The pokemon were still original and not garbage creations like they are now.

Best/Favorite Generation/s?
First and Third as far as pokemon go. Second for characters.

Favorite Pokémon (both legendary and regular)?
Arceus, Mewtwo, Scizor, Absol, Umbreon/Glaceon/Leafeon
I really hope you didn't mean just two.

Favorite Pokémon Type (if you have one)?
I'm partial to Dragon, Dark, and Ghost.

Best/Favorite Line Up?
I usually go strategically when I'm playing (no not hardcore like youtube battles). So whatever is strongest, fastest, has least weakness for that generation.

Anything else you would like to add?
Still haven't finished Black/White and Diamond/Pearl/Platinum