Have you considered Virizion as your EX and swapping the waters for Blends or Grass? (Or, for that matter, the Dark for Grass?) This would prevent Laserbank from trolling you, which, without Umbreon on the bench, KOs you in three turns. The reason I say to switch out the energy instead of simply adding some in is due to the fact that you would be cluttering up your hand with energy, and as such, demolishing consistency.
Furthermore, I would say that you desperately need Tool Scrapper in this deck, for you will face Garbodor and it will thoroughly ruin your day. Not only will Umbreon be disabled, but Smooth Coat as well. I would personally run two in this deck, as they won't clutter up your hand too much, and the odds of both being prized are highly unlikely. Therefore, your Garbodor matchup becomes better, and that way you might have a chance to take a KO of an EX by the time they get up another tool on Garbodor.
Also, Evosoda is kind of really awesome in this deck, as well, being able to drop the Umbreon as well as Cinccino when you desire it (except for when you put their basic down that turn, of course!
). As you would need to get out as many Umbreon and Cinccino as possible really quickly, I would run about 3 of them, as you don't want them cluttering up your hand late-game. Also, about Glaceon, I might run one less for an Umbreon, as you don't want -4 retreat on your Pokemon that has only one or two retreat, and +20 HP is much more desirable.
Also, three/four Skyla. Skyla will help you get that Plasma Badge when you need it, no questions asked. Without that Badge, your survivability rather depends on a flip, whereas with the Badge, you can take a lot more hits. Therefore, you should probably put in the Skyla, and a high number of them, as well, especially if you want to get out the Umbreon and Cinccino quickly.
As for your inquiry about Potions, I wouldn't go for Potions or Max Potions, yet I would go for
Super Potions in their stead. They discard one energy attached to you and heal 60 damage from you. Think about this math: Darkrai hits you for 90, and you flip tails. You have two Umbreon on the bench, a Plasma Badge and an Aspertia. You have 150 HP, and you have sixty left. Say you flip tails once more; you're KO'd, and game over. However, let's rewind; say you use a Phonewave, send a D-Mail back in time to tell yourself to put Potion in your deck, and the future changes. You find out, however, that you
still lost a Cinccino. Potion only healed 30 damage, and therefore that 90 became sixty, and as such, 90 + 60 = 150; still a KO. You, with this information, send another D-Mail, telling yourself to put in Super Potion in it's stead. As you rush back to the game, you find that you are not KO'd, instead you have 120 damage on you. With a confident smirk, you attach an energy from your hand to Cinccino, deal 100, and your opponent has a look like he just ate a piece of celery dipped in barbecue sauce. (don't eat that: it's nasty)
Also, you need more Aspertia City Gym: it's really good in this deck. It's an Umbreon you don't have to work for nor can it be Garbodored.
Plus, you rather need Mime, just in case you're facing Darkrai or other sniping decks, like Genesect with his Megalo Cannon.
Have you thought about your Ace Spec choice? In this deck, I might run Dowsing Machine, to get back important *CoughPlasmaBadge* items.
Also, I would also run a Super Rod over Superior Energy Retrieval. Or just a regular Energy Retrieval over that, because you don't have to discard, and you aren't going to need four energy in your hand at one time. Typically you're going to want one or two, especially when you're running Super Potion.
Just my two cents (and by two cents I mean wall of text) on the matter! Hope I helped, dude, and good luck with your deck!