The largest threat to this team is arguably the Scizor and Rotom-W offensive core, both being able to take what the other is incapable of taking. Keep in mind teams like this usually use some form of hazards (commonly Stealth Rock) to wear you down as you continuously switch to avoid being torn apart by their respective moves. A substantial amount of hazards render the Vaporeon/Whimsicott core ineffective, especially when in tandem with Ferrothorn, as Ferrothron sets up on the majority of this team and Espeon is hit decently hard with Gyro Ball, not to mention Power Whip. If not Ferrothorn, many of the Rotom/Scizor teams carry a grass type like Celebi, who has plenty of bulk to survive an Ice Fang or Crunch from Sharpedo and KO back with Leaf Storm/Giga Drain/whatever. Arguably the worst kind of Celebi you can face is the Tinkerbell set with Thunderwave, or the standard Nasty Plot set. Thunderwave cripples a Sharpedo switch in (which, already, Sharpedo is not a very good switch in to Celebi because of the risk of a grass attack), and it also severely cripples a Whimsicott switch in. To be completely honest... this can be so much of a threat that I'm not sure how to fix it.
Another omnipresent Pokemon that decimates this team is Thundurus. Thunderwave Thundurus is the most dangerous, and as said before, Thunderwave cripples the main sweepers of your team. Unless Kingdra has already made its way into battle, you are forced to sacrifice atleast one Pokemon and have Kingdra revenge. However, honestly, there are certainly not many teams that don't carry a Kingdra counter, as Reborn's tiers are still mostly what they are in early Gen 5, making Drizzle and Sand predominant in the metagame. Sharpedo can revenge, but it's counter is the same as Kingdra's counter, usually Ferrothorn. Even if you find a way to defeat Ferrothron (which, at this point, is unlikely), Thundurus can Thunderwave Kingdra or Sharpedo, rendering it almost useless. My suggestion to fix this issue is to put Lum Berry > Leftovers on Kingdra, allowing you to safely revenge Thundurus without risking a Para. This may also help allow you to use Outrage more than a few times, as the Lum Berry with stop the confusion and many, many, more statuses that can cripple Kingdra.
Last but not least... Serperior. Serperior was pretty dominant in the early says of Gen 5, as no one could figure out how to counter it and it was everywhere. Unfortunately for Reborn, it's still here. It can pull of a Leaf Storm on almost everything on your team, severely hurting it and then starts the destruction. Kingdra is your best bet at stopping it, but Serperior (at pretty decent health) can survive an Outrage and continue destroying with Leaf Storm. I really don't know what say to help you stop this 'mon, but you better hope you can Perish Song and/or Toxic. However, though, Choice Specs Kingdra, if I recall correctly, can OHKO Serperior with Draco Meteor.
Overall, interesting team, but not the best. It has alot of potential. Good luck~ And don't mind any spelling errors I may of made, typing fast has its disadvantages >_>
