Well, you have to catch something to trade me (and if you're early in the game, that something would tend to be something along the lines of, oh, a Patrat, or a Sunkern, or...). Since I already have a full Pokédex on Black and have an almost full Unova Dex on W2 (been slacking on getting it done and moving on to the National Dex there), I don't really have a need for anything particular, and being new to the last four generations, I naturally don't expect you to have anything nice to trade like a Shaymin or a Deoxys (and again, I have them in any case). :)
So yeah, just catch...something. I'll give you a choice of Keldeo. You can have a Lv.15 one that you can really start using after the first Gym, or you can have the nice one I just finally picked up today and, on the first try, had pretty awesome IVs for a Legendary with the lowest being at 17 for Defense, and HP I think being highest at an IV of 29 (to clarify, IVs start at 0 and max out at 31, never changing; you'll come to learn how these work over time, but basically the higher numbers mean more skill at that stat). I don't know offhand the nature of either, and have to look (and I can explain how those work as well).
So yeah...do you want the Lv.15 one (useable starting after the first Gym when trades - Events included - up to Lv.20 will obey you) or the Lv.50 one (useable after four Gyms, when up to Lv.50 obey, but not obeying again at Lv.51 meaning it's really after five Gyms)? Note again it would be a clone of the original; I'll retain the original in either case.
I have them on different carts. so can't give a FC to use yet. If you want to set up your FC for future use, you have to have the Pal Pad; once you have it, select it in Key Items and move about to get online, registering a Friend Code. That becomes the code I'd need (name doesn't matter, I can enter anything on my end and will likely use "Pokegla" to match your ID here), then you can register my code (I'll let you know if it's the Black one in my sig. or the W2 one I'll have to get you). Eventually, we can then meet in the middle room on the upper floor of any Pokémon Center (Victory Road and Pokémon League excluded) and trade. :)