Hope there aren't any great Pokemon that are exclusive to Shield - you can always trade for them, but requests on the GTS are wack (guess you can go ask on somewhere like Reddit though)
On the topic of version exclusives though, I was wondering what versions people here have played over the years. For me it was:
R/B/Y
G/S/C
R/S/E
FR/LG
D/P/Pt
HG/SS
B/W
B2/W2
X/Y
S/M
US/UM
Pokemon Blue: I never played the first gen officially, but my older brother will never let go of me deleting his completely filled Pokedex by starting a new game
Missed Gen 2 completely barring anime and Pokemon Stadium 2
Only played Firered for Gen 3 via emulator. It was alright, but I got bored after a while.
I played Diamond and Platinum for Gen 4, and I thought they were good times. Shame I never beat 'em.
Played Soulsilver and beat Lance. Thought the Kanto revisit was cool, but I got lost so I quit playing.
Pokemon White was okay, but Unova never appealed to me the same way Johto and Sinnoh did. Same with W2, though, I saw the improvements.
X was too easy. I ****ing steamrolled with mega Blaziken.
Skipped Gen 7 entirely because now I was seeing I wasn't into Pokemon.