I called 7 stores (all within a 15 mile radius, Chicago Suburbs) and asked the same question each time : "Do you have a promotion to trade in 3 GBA games to get a copy of Nintendogs?" and I got the following responses:
1) "Yes, but it requires a coupon"
2) "Yes, but it requires a coupon, I've been looking for it too."
3) "Yes" then a call back in about 3 minutes telling me "You need a coupon, nobody knows where to get it though"
4) "No, I don't see it in the computer"
5) "No, try back later in the week"
6) "I don't think its going on anymore, call back tomorrow when the manager is in"
7) "Yes"
I went to store #7 last night with 9 GBA games just in case there were restrictions on which games could be traded in etc. Walk in, clerk asked if he could help me, and I mentioned the promotion. He checked the computer and was suprised to see the promotion, and said there were no restrictions on what games I could trade in, and then mentioned that it was a killer deal and that he would do it tomorrow. Then he said just pick 3 games I didn't want. I gave him all 9 and told him I wanted to pre-order all 3 versions. No problems. Walked out with 3 pre-orders & an edge card w/ 2.03 on it (SMB 3 traded in for $12 for some reason.).
This is definatly a store by store phenonemon, and not a whole lot of people are aware of the deal. Hopefully the coupon will emerge for those that can't find stores to take the deal without the coupon. Best of luck to you all.