Well I dont know the complete story, but the international official nintendo tournaments it is not allowed. I think at one time Smogon must have had a bad reputation with that group, so now they are bending over backwards to appease that group. So they dont officially want people to openly promote pokeav. But on the wififinder, you are encouraged to tell others if you are using "legal" hacks, so it is kind of allowed. As long as you dont try to cheat an enter a torunament where they are officially banned, you are OK.
Most casual wifi battling or unofficial tournments it is almost assumed you will use pokesave or RNG pokemon.