Durant: No Ban
The ant has a lot of power but we are overlooking its Accuracy issues and poor Spdef/HP. This makes it a victim of scarf/quick volt switches and missing crucial hits(CB set mainly but Hone Claws set still suffers from this when Durant can't get off a Hone Claws).
As for ways to deal with Durant, I am going to focus on the Hone Claws set(no BP and no Thunderfang, who the heck uses those?) and the CB set. RU has Poliwrath, Cofagrigus, Magneton, Steelix, Qwilfish, and fast strong Special Attackers, which I think is more than enough for Durant. A healthy Qwilfish+Intimidate+Twave, shuts down any plans of a Durant sweep. Yes it can be easy to wear Qwilfish down but the same could be said about racking up LO(if you choose to run that) and Hazard damage on Durant. Since accuracy is always an issue for CB durant, it leaves qwilfish in a better position to outlast Durant. Magneton makes for a good offensive counter by roasting the trapped ant with HP fire. Cofagrigus can take away Durant's hustle power and Willowisp is back. Although Cofagrigus isn't the best method to deal with durant, its not uncommon to see this spinblocker be paired with another wall that can check Durant on a stall team. The true defensive counters would have to go to Poliwrath and Steelix who both just shrug off any attacks that Durant tries to do. However Poliwrath should watch out for CB thunderfang though.
There are so many revenge killers that can stop Durant or catch it in the middle of setting up a Hone Claws boost it isn't even funny. Scarf Manectric, Scarf Typhlosion, Sceptile, and many more. It isn't hard for a Sceptile to KO it with Focus Blast or choose to Sub until that Hustle accuracy kicks in. Maybe for an offensive team its a game of which speedy killer outlasts the other, but an offensive team should pack enough pressure that Durant can't reliably set up. It's hard for Durant to enter the battle against an offensive team where it is likely that 5 out of the 6 pokes can ohko the bug. That is another area I want to address, the ability for the Hone Claws set to actually set up. Being vunerable to burn and paralysis, unless you catch the right poke in at the right time, Durant is most likely going to take a good chunk of damage or get crippled by status. CB Durant on the otherhand could lock itself into a move where it allows the opponent to set up afterwards or just not even hit due to Hustle accuracy.
Overall, not many great counters, lesser checks can be flinched KOd and worn out easily, very powerful attack, but it comes at a big enough price that Durant shouldn't leave RU. Hustle accuracy(especially for CB set), easily revenged, and not many switch in/set up opportunities due to its weakness defenses. It's close to being broken, but not close enough in my opinion.
Sharpedo: No Ban
Priority weak(even resisted honchkrow suckerpunch does a ton), fragile as hell, and definitely has its counters/checks. Does not even deserve to be nominated for a vote in my opinion. Poliwrath and Ferroseed(watch out for HP fire but even that will fail to OHKO) are the counters to any set Sharpedo runs while physically offensive sets get walled by Qwilfish, Spiritomb Mandibuzz, Alomomola, Tangrowth, and Crawdaunt. Depending on whether or not Sharpedo runs HP fire or Ice beam on the mixed set, it will most likely share most of the counters of the physical attacking set. Hitmonchan, entei, and even honchkrow all do a fine job of killing sharpedo with priority. Most offensive threats like Feraligator, Druddigon, TR cofagrigus won't get OHKOd so it isn't likely to force many switch outs until the late game. Not being immune to any hazards, status, and being pretty much forced to run LO and Protect doesn't help sharpedo either. Great late game cleaner, not much more than that.
"Even so, those words were very important to her. It offered a shred of solace to the broken-down heart of a monster. Having inhabited the depths of darkness for so long, she could no longer integrate herself in the world of light."