If Meloetta could start in P form, it could actually use Adamant on the sets, and still outspeed Timid Lati@s, having higher speed and attack. Unfortunately, it has a lacking movepool, and doesn't have the capabilities to OHKO the Lati@s or Keldeo.
The problem with this is that if Meloetta-P were to become common, then it would REQUIRE to run Jolly in order to speed tie with itself.
252 Atk Meloetta-P Close Combat vs. 4 HP / 0 Def Meloetta-P: 422-500 (123.39 - 146.19%) -- guaranteed OHKO
With a Life Orb, however, its power is still quite formidable even without Adamant, and it can threaten Latios with U-turn much more than with Ice Punch since it can switch to a counter.
Crobat could potentially threaten Meloetta, however, despite its 4x resistance to Close Combat, it would still be unable to switch in without risk.
252 Atk Life Orb Meloetta-P Return vs. 0 HP / 0 Def Crobat: 259-305 (83.27 - 98.07%) -- guaranteed OHKO after Stealth Rock
If Meloetta runs a Choice Scarf instead of a Life Orb, then Stone Edge does the same damage.
252 Atk Meloetta-P Stone Edge vs. 0 HP / 0 Def Crobat: 260-308 (83.6 - 99.03%) -- guaranteed OHKO after Stealth Rock
And of course, Relic Mixed would still remain my personal favourite set. Chances are these dedicated Meloetta-P sets would be a lot more common, making it all the more satisfying to bluff a Choice set and then use Relic Song after luring in an unsuspecting physical wall. After all, it would be a shame if an entire half of Meloetta were to go to waste.
And here's another one.
What if Rotom (all formes) had the abilities Motor Drive and Prankster? This is pretty easy to rationalize, as almost all of Rotom's flavour is based on motors, even its name. And they're shown to generally have a prankster-like personality.
Motor Drive would certainly help its sweeping capabilities, letting it occasionally boost its somewhat lackluster 86 base speed and providing an electric absorber for Rain teams. Prankster would help its supporting abilities, hitting sweepers with a priority Thunder Wave or Will-o-Wisp to stop them in their tracks. And of course Levitate would still remain valuable defensively, removing its weakness to the ever-common Earthquake. Rotom-W becomes all the more versatile.
Interestingly, it would still remain somewhat safe against ground type moves, as players may be hesitant to risk wasting a turn with Earthquake against it. However, it would still lose the ability to switch in.