I actually played Gen 1 first because we had Pokemon Stadium and I could play Pokemon Blue by using that thingy you could buy to play Game Boy games on the N64 (which belonged to my Cousin). But the first console I owned myself was a GBA SP and my first Pokemon game was Ruby. I remember I was like 7 years old and didn't know what to do in the game at all xD.
The games I have/had are/were these (some I've lost or are defective/no longer playable now):
Gen 1: Blue, Yellow.
Gen 2: Silver, Gold.
Gen 3: Ruby, Sapphire, Emerald, Fire Red, Leaf Green (Leaf Green was stolen from me on a bus -_-).
Gen 4: Diamond, Pearl, Platinum, Heart Gold, Soul Silver (I lost Pearl on a trip to the Czech Republic).
Gen 5: Black, White, Black 2, White 2.
Gen 6: X, Omega Ruby, Alpha Sapphire.
Gen 7: Moon, Ultra Moon.
Gen 8: Sword.
Also back in the day it was actually pretty difficult to even get games for me. We had 2 shops which had games and both were sold out quickly lol.