I got myself confused on the screenshot showing 6 of the same legendary pokemon, then when i happened to look at bulbapedia's info on breeding I was amazed. If you put a ditto and a pokemon of your choice into a day care, after a long time you will give life to another of the pokemon you chose to raise, doing that can eventually can get you multiple blaziken, or mewtwo, or any other awesome pokemon, but you have to level them up to show their supreme power.

bananaeater99 : You cannot breed legendary Pokemon, (I'm not sure about heatran from 4th gen but definitely no other legendary. Now that I think about it in the 3rd movie lugia could make a new baby but that's a completely different story.)

i have done that before and i breeded my starter and my friend breeded theirs and we traded and i got nearly every starter pokemon doing that it was really fun. iN008: 3rd movie? the 3rd movie had the legendary pokemon entie and a load of unkown so what does that have to do with lugia?

TheeDragoniteMaster : Sorry second movie*
Sorry but originally the first movie was in two parts thus I keep remembering it as two movies... so sorry for the mistake.
Never the less, it was talked about in the dialog so :p

As people said before you can't breed legendairies and I think he meant the second movie with articuno moltres and zapdos and lugia it's not my favorite Pokemon movie but it was pretty good

Like the others said, you can't breed legendary Pokemon since they're genderless(except for Heatran), but it's still a good way to have a lot of other non-legendary Pokemon of the same kind. Oh, and TheDragoniteMaster, I think you're not talking about the second movie, you're talking about "The mystery is History, a Parent trapped!" and "A promise is a promise", both are regular amine episodes.

No legendaries can breed except Manaphy, and even then you don't get another Manaphy.  This isn't how Blackustar got those six Rayquazas.  Obviously, I don't know for sure how he did it.  You'd have to ask him.  But my guess would be he used the Battle Tower glitch.  Here's what Bulbapedia says:  


Due to improvements of the games and hardware such as the capability of the Game Boy Advancelink cable to send and receive data at the same time, the auto-canceling of trades if something goes wrong, the lack of need to save while changing PC Boxes and new data corruption protection, both methods exploited in the first two generations to clone Pokémon were essentially removed for the third. While Pokémon cloning was completely absent on most games of this generation, the glitch returned in a different form in Pokémon Emerald, where the Link-Battle mode of the Battle Tower saved only the party and Bag of the player, even if he or she chooses "no" when the game asks to; this was due to the game's need to save a massive amount of data and check connections. Like in the methods from the previous generation, if the save is interrupted at the right moment, up to six Pokémon can be cloned at one time. However, unless you have a Pokémon that you are willing to lose, you can only clone five. It is also possible to clone numerous items at once.  


I'm not sure if the glitch still works on Vizzed emulators, and of course you'd need netplay.  But it seems like the most likely explanation.

Honestly the use of legendaries in battles is just cheap altogether... It makes the battle to easy.

There is a possibility to clone pokemons on pokemon emerald
my friend used to clone legendary pokemon.. i don't know how he did.. it was like a kind of glitch. he puts he's puts a pokemon from he's team to he's storage and saves he's game. during saving he shuts down he's gba and when he restarts it apears that both of the same pokemon is as wel as in he's team as in he's storage..

i never used this kind of technique or glich. i dont know how it works completely. but my friend used to clone some of my legendary pokemon to back then. i traded them from ruby. he cloned some of my pokemon and keeps one for he's self and gave me 2 in return. i really don't know how he did this job.. there is also a ligal way to clone. but you first need to beat the 4e and be able to access the battle frontier.. as from what i once readed its still impossible to clone legendary pokemon in the ligal way.

i have and wil never have any clue of how to do both em . i once readed the ligal part.. and saw my friend cloning with the glitch. but i tried it like 50 times one a loaned emerald game.. but i just couldn't succeed my cloning progess.. so i stopped trying. now i read this topic thinking back of the old times..
my friend once told me he had a hatched lugia on pokemon silver.. didn't see it though so it might be a joke.. for people who wants to hack.. consider to use the ligal way.. i don't know how to do it.. but google might know it..
don't try the glitch as it might corrupt your whole game..
also the ligal way needs full play time to work. thats one thing i remember.

back to the main topic i think.
you can breed every none legendary pokemon. as i know even pokemon without a gender which are none legendary.
breeding can have a positive effect on the natural IV's of a pokemon. and also provides alot of cool experimental Egg move sets.. like: treecko can be learned dragon claw by breeding. and feebas can learn dragonbreath/dragon pulse during breeding.
also the EV's of the mother's pokemon can effect the Iv's of the hatching baby pokemon.
as i can remember also the EV's of the male parent might be used in the IV's calculation but i'm just human so don't be afraid to correct my faults
i hope this is kinda useful to you guys.. good luck..

Greetings, Yngwie
PS : mand'alor did you copy paste your information?..

It was copied from Bulbapedia, like I said.  I'd link to the page, but I don't think I can post URLs yet.