The fake pull to the ankle pick is a classic. Only lighter nimble guys seem to be able to pop back up fast enough to hit it though. Sumi gaeshi seems more consistent across weight classes.
Fundamentally I think unless starting the match in top position is advantageous for your gameplan, there's no reason at all to consider takedowns in a BJJ sport context. That's really their only function in a tournament as far as I'm concerned.
It's either double guard pull, one pull/one plays top, or two top guys. Takedowns only matter in the last case. And usually even in that case it's not a matter of actually scoring with them but rather forcing the other top player out of his A game when he has to pull guard.
The easiest way to get on the board seems to be double pull and then immediately come up for an advantage.