Here's some changes I would suggest. I will start of by telling you what I think should be taken out.
~Subtractions~
-1 Cleffa: Normally 1 Cleffa is enough to get you through a game so taking one out shouldn't really hurt. You also don't really want to use Eeeeeek at the begging of a game because your first priority should be using Thundurous's Charge attack turn 1.
-1 PlusPower: These can be very useful I must admit but I think 4 is a little over the top. You already have Junk Arm to reuse some if needed and for really bulky Pokemon that Thundurous can't KO without multiple PlusPowers you should just use Zekrom instead.
-1 Eviolite: Another very helpful card that you play but again I think you're just playing 1 too many. When you get them they are almost always useful but you shouldn't really need more than 3 and if you are ever in the situation where you really need another one you can probably just use Junk Arm to grab it.
-2 Defender: I don't think these are necessary unless you play Zekrom but even then I think Eviolite does a good enough job shielding Zekrom as well as all of your other basics.
-4 Lightning Energy: I think that 10 Lightning Energy is plenty and 18 total Energy is just too much so taking out a few should help.
-4 Rescue Energy: Again, I think you're playing a few too many Energies and I don't think Rescue Energy is all that useful when you're primarily attacking with basics.
Those are all of the cards that I think you should consider taking out . Now on to the cards that should be added to replace them!
~Additions~
+2 Zekrom BW: This guy is for when Thundurous just isn't enough. Being able to hit for 120 or more, with PlusPowers, can insure you those KOs on bulkier Pokemon that you can't normally KO.
+2 Tornadus EP: This guy is in case you don't want to accept a near auto-loss to Donphan. Donphan steamrolls a deck like this if you allow it to get even a little setup but with Tornadus it allows you to put up a nice fight. I know Donphan Prime isn't super popular right now but I do still seem them from time to time.
+2 Pokemon Collector: 4 Pokemon Collector is a staple in pretty much every deck in our current format. It helps you get setup faster if you have it turn 1 to let you search out things like Thundurous and Tynamos so you can hopefully get a turn 2 attack as well as an Eelektrik to help with the energy recovery.
+3 Pokemon Catcher: Just like Pokemon Collector this card is a staple in almost every deck, with the exception of trainer lock variants. Pokemon Catcher will allow you to stay ahead of the prize exchange as well as disrupt your opponents setup sometimes.
+4 Double Colorless Energy: Since you are playing Zoroark I thought this would be a nice addition to the deck to get your Zoroarks ready to attack even faster. And since Tornadus uses 3 Colorless Energy to attack this will make it easier for you to attack with it as well.
~Other ideas~
So looking at your list I saw many changes that could be helpful, some big and some small, but in the end you have the last say on what gets changed so I didn't want to make a super long list of changes. The changes I did make were the ones I thought were most important for your deck. However, I thought I would give you a shorter list of things that might also help but aren't as necessary as the other changes.
+2 Professor Juniper/
+1 Engineer's Adjustments: I saw that your list seemed to lack just a bit of draw support so adding 1 or 2 more draw supporters may help. I would say 2 Professor Juniper is more solid but if you don't have enough room just 1 Engineer's Adjustments will probably do just fine.
+1 Super Rod: In case you want a little bit of Pokemon recovery in your deck. Although it's not needed I'm sure it can help you in some situations.
+1-2 Switch: These are primarily to help you when your opponent drags up one of your Eelektriks and attempts to stall or attack around it. They can also just help with bad starts in general or when you're having trouble getting something like Zekrom out of the active.
If any of those additions interest you there wasn't much I saw that you might be able to take out except for possibly the Zoroark line. I'm just not sure how much Zoroark helps with this deck but I didn't really want to take it out either because you probably know more about how it works so you'd be the better judge on whether to remove it from your list or not.
~Conclusion~
I seriously think your deck can be very solid with some changes. I played a similar deck at Cities last weekend and although I didn't make top cut, I do think I came pretty close and I still had a lot of fun with the deck. If you have any questions about the changes I suggested or just about the deck in general feel free to ask or just share your thoughts. I hope that by posting this that I've helped you or at least gave you some ideas with your deck. :]
/me drops dead from typing up his exhausting post...
*Celebi drops dead from reading this this exhausting and long post and then contributes it to Afro-G's Grains of Sand.
