Well, prepare yourself, because the description is gigantic!
First, he's from the Richard adventures. The Pokémon time line says that Pokémon XY passed at the same time of Pokémon B2W2. Richard adventure in Unova was in BW... 1.
And, his Kalos adventure pass after the Hoen Mirage Spots Expedition (see the summary), to come back to Taya. Kim have a Kalos adventure too, but was a bit after, probably, a bit more than half year.
Now, about the OC. Why Rock? Rock was the character name of my first Pokémon Y "run". Reference to Rock Silver, from one own history. (Zero Silver dad!)
He and Shauna are friends. After, he meet Y, X, Trevor, Tierno... and, Richard and Katarina.
If you note, his arms have marks (better in left arm), this is from Honedges and his Doublade.
If you read the Pokémon Y Honedge Pokédex entrie, it says:
"If anyone dares to grab its hilt, it wraps a blue cloth around that person's arm and drains that person's life energy completely." (Thanks Bulbapedia!)
But, he haves a mysterious force, that makes he stronger than the pokémon, so, HE own the POKÉMON!
Nah, he just don't have his soul eat or possessed.
And yep, he have a Honedge, that evolved into Doublade. Sometimes he use it as a sword, and this thing occurs. There's too the Honedge that possessed Shauna. This time, he used the own Honedge, to defeat it. (the Honedge)
Well, hope you like it. Thanks, now have fun.
(The sprite was medium, ok?)
(Probably, there's english errors. So, say the correct writing)
Kalos OC! Pkmn Trainer Rock - Sprite