Quoted By:
R/B/Y - "Red, Blue, Yellow"
G/S/C - "Gold, Silver, Crystal"
R/S/E - "Ruby, Sapphire, Emerald"
FR/LG - "Fire & Leaf"
D/P/Pt. - "Diamond, Pearl, Plat'."
HG/SS - "Heart & Soul"
B/W - "Black & White"
B2/W2 (If you use BW2, kill yourself) - "Black 2 & White 2"
X/Y - "Ecks & Why"
OR/AS - "Ore-ass"
S/M - "Ess 'n Em"
That's the correct abbreviations and how to appropriately say them. OR/AS is spoken in its abbreviated form because the full titles are too fucking long. Platinum is abbreviated to "Plat". Sun and Moon is spoken in its abbreviated form just because it roles of the tongue really well.
And seriously, if you use BW2, just die. Such a ridiculous abbreviation, and I hate how it's fairly common.