I didn't officially enter the research group but I wanted to post some of my experiences with Meloetta, specifically a CM set I made.
Meloetta @ Leftovers
64 HP/192 SpA/252 Speed
I have to say I have been pleased with the results I achieved with this set. I would primarily use it to set up on bulky walls such as Slowbro/Milotic, usually switching in on a predicted ice beam or weak STAB. Since Meloetta can be a bit unpredictable, their first instinct is to status which is why Sub is in the set. After a single CM Meloetta will become quite bulky on the special side, and reaches surprising power with it's STAB Psychic. Sub also helps ease prediction when you have a feeling your opponent might switch, which leads to your opponent being forced to sac a poke to prevent a sweep. It also has the added benefit of protecting you from Sucker Punch mind games, the bane of every Psychic type sweeper.
The best advantage of this set is the surprise factor. I lost count how many times people switched in Slowbro/generic wall, expecting a physical set, only for me to start setting up in their face. Their next move was to toss a status, expecting to cripple my sweeper, only for me to set up a Sub and become even deadlier.
I will admit the EV's are a bit arbitrary but they seem to work out. Max speed means you outpace a fair portion of the bulkier side of UU. Speed can be vital vs special attackers since you obviously want to CM before their attack. You might think with the Speed + nature you would miss some power, but with SR up and a single CM it was not difficult to grab OHKOs. The small investment in HP meant bulkier subs and more recovery from lefties, which made it easier to grab multiple boosts if necessary.
As for the attacks chosen, I only had 2 slots available so I had to choose STAB+ coverage move. Since Meloetta does not receive any notable Sp normal attacks, I had to go with Psychic. Tbolt rounded off the coverage nicely, hitting bulky waters and STAB resists hard. The exception to this is Krookodile, who is immune to both attacks. I do not think there is a better single coverage move, since there are resists for every notable HP. This could be solved by going CM + 3 attacks, but as I stated earlier the protection granted from Sub was invaluable and Krook never proved to be a significant problem.