Who here uses uncommon Megas (Menetric, Medicham, Blastoise, Aerodactyl, etc) competitively? I'm interested to hear how you use them, who their teammates are, and how well they perform.

I use a Mega Houndoom personally. The team she's on is still being developed, but its done enough that I can take it on the Ranked Battle Spot with some stand-ins.
Anyway she rolls with a Ninetales and a chlorophyll Venusaur at the moment. So far they have pretty good synergy.

Ninetales usually leads and brings out the sun. Houndoom is pretty fragile so I really need to wait for an opening to bring her in. I found a good way to do so is use Venusaur and bait a fire or psychic attack then throw in Houndoom to absorb either (has flash fire prior to going mega). Once Houndoom's out, mega'd and in the sun it can usually do some pretty major damage. Solar Power sunlight STAB flamethrower is retardedly strong and her speed is pretty up there, plus I gave it Destiny Bond to pretty much guarantee at least 1 kill. M-Houndoom's real problem is that you can't always create conditions for it to get in safely, so I do also have a Mega Stone on my Venusaur in case I can tell Houndoom isn't going to able to pull anything off.

tl;dr M Houndoom is a fucking terror if it can switch in safely and under the sun, but its not very reliable and goes down fairly easily.

In case anyone was wondering EV spread is
252 Sp Atk
252 Speed
4 HP

and Moves are
>Destiny Bond
>Flamethrower
>Solar Beam
>Dark Pulse