RedBownShipping is a crack pairing to most people. Of course it is; Gary and Melody have never even met each other....Or have they?
Gary was Ash's rival through Kanto and Johto, but then Ash beat him in the Johto League. After this, he went off to be a researcher like his grandfather. He returned in one chronicles episode and a few Diamond and Pearl episodes showing us he's still working towards his dream of research. However, throughout all of Hoenn, he never even appeared once. He didn't even see Ash until the very last episode of the Advanced Generation. He was missing when Ash came back from his Hoenn travels and no one saw him throughout all of the Battle Frontier saga. That leaves us with a question. Where was he?
The immediate assumption is that he was busy with field work. However, we know Ash and Gary are close friends, and had he been anywhere nearby, he probably would have made an effort to come and see Ash at some point. He never did, and thus, he had to have been somewhere far away. Of course he could have been in Hoenn or Johto or somewhere, but think. Where would he need to go for research? Perhaps his grandfather would suggest something. As a famous researcher, surly Gary would go with his idea. And where would Oak want to send him? Perhaps somewhere Oak had been before? A place catastrophe had struck almost a year previously? That's right friends. This is Shamouti Island and the surrounding Isles. Wouldn't Oak want to know how the place had recovered and developed? Wouldn't he have questions about the legendary Pokemon living there? Had the birds stayed on their Islands or been traumatized and left? And what had become of the beast of the sea? How was he? Surly there are many question Oak must have had swirling around his head.
But the professor cares about his grandchild and wouldn't send him without a contact. This contact would certainly be someone knowledgeable about the events; someone who had been out in the field when it all went down. Someone who lived there who could explain to Gary how things HAD changed. And what better contact then the girl who had summoned the legendary creature when the disaster had happened. He would call Melody.
It all fits. Brock has told us it takes nearly a month to get to the Orange Islands and who knows how much longer it would take to get to Shamouti. It would explain why Gary couldn't come back to see Ash and why he only returned at the very end of the Advanced Generation. And just because we didn't see it happen doesn't mean it didn't.
It isn't necessarily crack.
Think about it.