From what I can tell, Olimar is the least rare of all the Wave 5 general release.
The Retro Pack was pretty ok stocked at Gamestop (It was mostly preorders but they had like 1-2 for general sale, maybe more in back since its a tiny store), and I go into Target often on my Lunch and I see tons of Dr. Mario there making him I believe the first really common Store Exclusive.
Apparently Shulk, Lucario and Greninja are going to be breaking exclusivity soon as they've been spotted in Best Buy's system (And Shulk in TRU as well), TRU's also getting a restock of Little Mac, Fox, Villager, Captain Falcon, Wario, Lucario and Greninja so maybe the stock issues are finally settling.
Mii Fighters are all around typical MSRP on Amazon right now for the Japanese imported figures if you don't want to wait till November to get the three-pack.
Apparently an update was rolled out and we're getting a Super Mario Maker stage in both the 3DS and Wii U versions alongside that [tornado fang]ing Pirate Ship stage from Brawl on the Wii U version. Also another spattering of mii costumes (Most notably Viridi and a bunch from Monster Hunter, what, is the crossover frenzy from that spilling over their original content into other crossover games?). Apparently the 3DS version also gets the Duck Hunt stage now.