I thought I worded that quite nicely. :\ EVs are only gained when experience is in battle. You don't gain experience in the Battle Tower, so you don't get EVs from it.
In addition to this, you will not be able to gain EV's from wi-fi related battles. That goes for the Battle Frontier, Battle Tower, Wi-fi battles downstairs of the Pokémon Center, and I think that's about it. If there are more battles to where you do not gain EXP Points that I left out, those will not count either.
I hope this clearly states what you are looking for...