Just got back from a Fred Meyer's in Vancouver, WA and was able to successfully get the $50 gift card twice using the 3DS B1G1 1/2OFF coupon. Only needed to buy 4 games per transaction, (2) @$29.99 & (2) discounted @ $14.99 worked just fine for me.
I also bought Pokemon Sun/Moon, so not sure why it worked for me and not IO? Might be the order they scanned the coupons in. I made sure they scanned the gift card coupon 1st, then the B1G1 1/2off coupon, & the savings certificate last.
It is YMMV on them doing the gift card first. At my local store they are onto it and don't allow it first.
But still I'm surprised it worked for you. I went to another store just now and bought 6 games. I was hoping just to get the $35 card for the 3 non-discounted games. But this cashier insisted on doing the $50 GC first! So, "great", I thought. But when he finalized the transaction it only discounted 2 of the games to 50%, and it was the 2 cheaper ones. I had bought 2 $39.99 games and 4 $29.99 games and I only had two $15 discounts. I figured the 4 game gift card promo negated the 3rd B1G1 50% off discount. So that was actually worse than getting the $35 gift card for 3 games (since I gained $15 on the gift card but lost $20 on the discount). Fortunately he just did an override and rang up one of the $39.99 games at $19.99 and I ended up getting the discount.
So I ended up paying $135 for 6 games and a pair of $14.99 headphones (since I was 6 cents short of $150 with the 6 games ). After discounting the $50 gift card, that comes out to about $12 per item (for each of the 6 games plus the headphones). Not bad considering I had a couple of $39.99 games in there too.