IOS37 I don't think it was actually on Brawl, if it was well no one's had anyproblems with it - and i've subsequently updated my Wii since then. Even if it was in there Nintendo haven't bothered to activate it. It was rumored to be on Mario Kart when that first appeared sending people into a frenzy of brickblocking etc. Worried that half their collection would become inoperable.
IOS37 has nothing to do with the editing of games. IOS37, from what I understand is more to do with region coding and was released in direct response to Datel's Freeloader. Region patching from chips at the moment isn't 100% anyway, and i've had no problems using a combination of free loader and the region patching software out there, with one or two known exceptions, eg No More Heroes. IOS37 should prevent freeloader and other region patching software from being able to operate. A quick google search will reveal more on the subject. The quick way to prevent this is if you have a PAL Wii use PAL games, if you have an NTSC/U Wii use NTSC/U Wii games and so on. At the moment like i said this is not really a problem as no game has had this activated yet to the best of my knowledge, and I'm sure someone will find a way round the coing sooner rather than later.
IOS37 - WiiBrew
Edited games at the moment are uncommon as well. SSBB is the only one I've seen and that was to make it fit on a single layer disc. At the moment it is the only DL disc so you shouldn't need to worry about that either at the moment.