Anyone here play competitive pokemon?

I've just started this gen (XY) and I'm trying to use Lucario in my team. However, I've found him to be really squishy and difficult to set up. Whenever I get into a battle online whenever I try to SD, the enemy usually just counters and OHKOs him.

I keep reading on places like Smogon that he is a really good and really dangerous, but I just can't see it.

Does anyone have any tips on how to properly use Lucario and/or how to set him up? Thanks.