Popped in to my local Sainsbury's (Emersons Green, Bristol) and not only do they have the 2 for £20 offer on Nintendo Select games, but all Pokemon games were reduced from £32.99 to £24.74, considering they cost this second hand on eBay it's a great price!
Pokemon Omega Ruby
Pokemon Alpha Sapphire
Should be national, looks like Sainsbury's are discontinuing their 3DS lines. I haven't seen this online so no links available.