There are certainly big guy moves, but I'd encourage you not to try to catagorize the moves until you've tried them. Everyone develops their own game over time and your game will be the result of what you are taught, what you like, and what works for your body type.
Try everything and then decide what to incorporate into your game.
Without knowing you, I'm guessing that you are probably stronger than most guys you roll with, but not as quick. If this is the case, you'll want to work on controlling your opponent. Use your weight to your advantage and right away learn about hip control. I think Cookie Monster posted a link on this site on hip control that was great. Learn how to control your opponent using your weight and lots of opportunities will open up.
Try not to fall into a trap that I see big guys fall into. Because you are probably stronger and bigger than other guys, you will probably be able to force submissions like the Americanas just by using superior strength and size. That is fine, but try not to make it your bread and butter, because if you are just forcing things with strength, you'll be screwed when you face guys in competition that are your size. Look for opportunities that your opponents give you as opposed to forcing the action using superior strength.