All of the lucario move sets you've seen have ice punch, because it works really good on him.
You can't get ice punch in X/Y. You can give it to him for 10 red shard - Driftveil City (Black/White). Or, if you have OR/AS, you can hive it to him for 10 green shard - Fallabor Town.
If you want a replacement, there are other options that works great.
I'm assuming on your lucario, you would have a fighting and steel move - since most of his moves are these, plus for STAB. Other than ice, he can learn ground and dragon (not TM included). This way you can include 4 more super effective types, plus dragon to be neutral to all the other types.
Your Choice! Hope I helped! :)