^^ Definitely go for EQ over Twave, regardless of your item. Electivire isn't bulky enough to lay status. Also, while those are both good suggestions for an item, a third option to consider would be the Expert Belt, which is viable on him due to his huge coverage. I like the idea of a scarf Electivire however.
* * *
Gardevoir @ Gardevoirite
Nature: Timid
Ability: Trace / Pixilate
EVs: See explanation
-Wish
-Calm Mind
-Hyper Voice
-Shadow Ball
This is for UU, not OU. Gardevoir has long been my favorite Pokemon, and I've always wanted to make her work in higher tiers. After a lot of trying, I've finally convinced myself that Gardevoir just wasn't meant to be a sweeper; she just lacks enough speed and power, and while she could previously fix one with a choice item, it left her wanting for the other. However, between receiving a Mega and gaining defensively awesome Fairy-typing, I think she finally has the tools to make it in at least UU (although I'm still very skeptical that she'll work in OU). As a bulky Calm Mind user, I think she will excel.
Calm Mind has been the only really successful way of running her anything but support in the past. It boosts both her offensive and defensive capabilities, so as long as she can avoid physical hits, she has a lot of staying power. Combined with Wish, she could be very difficult to take down. Hyper Voice (as a Fairy-type move due to Pixilate) and Shadow Ball give her perfect neutral coverage, and fairly unresisted coverage at that. Psychic is redundant with Fairy offensively, and Thunderbolt or Focus Blast don't hit very much harder than she can with Fairy/Ghost. Furthermore, I know this is consideration outside of the set as a standalone thing, but the team she would be fitting onto already has a physical wall, can handle her weaknesses, and would benefit greatly from a Wish passer; it would however benefit from something that can tank special hits easily, like a CM Gardevoir could.
The one thing I'm really stuck on is the EVs. In-game, I have a shiny, flawless, Timid one, so Timid is the nature I have to go with. I'm guessing I want to max her Speed, or at least get close enough to outspeed a benchmark. Base 100 Speed in her Mega form is nothing to scoff at, especially in UU, so I imagine just maxing it is probably the way to go instead of trying to be cute with it though. After that, obviously the rest gets dumped in Special Attack or HP. I'm thinking I probably want to put it in HP, both to make her bulkier (her primary role, afterall; remember, not a sweeper) and to allow her to pass bigger Wishes to her teammates. However, everything I'm reading about how to use Mega Gardevoir maxes Special Attack first and figures out everything else later. I think I'm pretty solid on everything about this set but the EVs; any suggestions here would be appreciated.