With these code you can rebattle + catch Pokemon you can only get one time. This code will not work if other codes are one besides the (M) code. When the code is on, go to the place where you see/get the pokemon, then save, then you can turn the game off, use a different code "like a shiny code:)", then catch the Pokemon. Have fun.

Re-battle Latios/Latias & Mew (DMA)
F28AEEBB E96723FB

Re-battle Lugia & Ho-oh (DMA)
719C9601 0AFEE31A

Re-battle Deoxys (DMA)
404F4203 DEDBC3F7

Re-Battle Groudon & Kyogre (DMA)
67DAF8E7 3F6C38D6

Re-Battle Rayquaza (DMA)
67BD0A40 0DD73EBA

Yes, you will be able to catch the legendaries over & over again with these codes.