It depends on if it's a wifi tourney or a live tourney. If it's a Nintendo live tourney, probably not, but if it's a Nintendo wifi tourney, you can even used hacked Pokémon, so long as their legal. On smogon university, anything is fine as long as it abides to all of the clauses and is legal.
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.
I RNGd some Dittos to get perfect IVs and I then breed with them to pass down the desirable IVs until I hatched an egg with the correct nature, ability, and nearly perfect IVs, and in some cases, in which I had to hatch an outrageous number of eggs, the right hidden power type.
I know a little bit about it.
I did breeding and IV training for about 6 months. But then I learned how to use pokesav and now I use that to make all my teams. I hope that does not offend you.
But I did do some more breeding when black2 came out with join avenue.