Head canoned.
Steven is like Ryu from Digimon.

Heh?

He travelled between two universes.

I feel like Swampert goes better with Gaim due to the color scheme. Meganium & Bravo go together for the same reasons. I also think these would match up well:

Baron/Blaziken
Ryugen/Dustox
Zangetsu/Gallade or Gardevoir
Gridon/Ursaring
Kurokage/Staraptor
Knuckle/Hariyama
Zangetsu Shin/Volcarona
Marika/Miltank
Sigurd/Flygon
Duke/Druddigon

Still haven't caught an Adamant Groudon... This is taking an eternity. :(

Adamant Synchonise?

I could send him an adamant synchronize elgyem but unfortunately when you battle Groudon you can't use you're PokéNav.

Because going through the effort of finding an Adamant natured Pokémon with Synchronize wouldn't also take forever. Right.

I also choose not to trade in a game until I have completed it.

Shiny Metagross (both the one I got from the event and from the reverse GTS yesterday), Gallade, and Lopunny are all trained and ready for mega evolution online! The Metagrosses (Metagrossie? Whatever the plural for more then one is) are two slightly different sets so they are both flexible.

Managed to get the Eon Ticket through Streetpass today! Now to get to a point in the game where I can actually use it :lol