My friend and I discovered this program, and he said that if we set the Pokemon up to seem like it has been caught and/or hatched through regular gameplay, we can enter the Pokemon we got from the program in a VGC tournament. We made a Shiny breloom last night, and I saw no suspicion in it's OT and stats. Will Pokemon from PokeGen pass the Hack Checks in these competitive tourneys, or can they easily be spotted and so you wont be able to participate? Smogon has been down for two weeks, so I can't find a straight answer for this...
Believe it or not, it is possible to use PokeGen, PokeGTS, Pokecheck Pokemon as long as their EV and IV isn't over the border wich is 510 in total for EV and 31 on all stats for IV. Your Pokemon's location must also be viable. It isn't allowed to know any hacked move or illegal move. If all this things are kept, you can actually join the Tournament. You can even participate in wifi-battles. I should warn you that when abused you might not be able to use them on wifi for a short while.
Source: Eyewitness