The Elite Four Champion from every perspective Pokemon Region in the world was invited by King Rivier and Queen Sysha, the monarchy of my Dakem Region, to Avalon City, to participate in a battling tournament to find out who really is "The Best of the Best."
There is Lance, hailing from the Indigo Plateau, the location of the Elite Four for the sister regions of Kanto and Johto.
Wallace came from Evergrande City in Hoenn, Then there is Cynthia, from northern Sinnoh, and Iris and Diantha from the far off regions of Unova and Kalos, respectively.
Seated with them are Kira, the resident Champion from the Dakem Region, and finally Red (Ash if you prefer) who is arguably the strongest trainer in the world, and was drawn from his isolation on Mt. Silver to participate in this most epic of tournaments!