If you want a challenge Google blaze black 2 or volt white 2. They're hacked roms that are much more difficult than the normal game. You can also get every single Pokemon in the game all by yourself, no trading. He changed trade evos to use an item like a stone evo. Don't remember the guy's name, but I think its Drayano. I highly recommend it.
But since you haven't played ANY gen 5, you might want to start with the first black/white. It'll make more sense story-wise and it's fun only using the gen 5 Pokemon on your first run through unova. But definitely try out those ROM hacks above.
