Okay, your team is to be appreciated for the effort you put in creativity, but really, Muk is a terrible choice in OU and turn what would be a good team in a not-so-good one by just being there. Your team is already dangerously close to being 6-0ed by RP Sheer Force Landorus, and Muk gives a huge opportunity for it to set up, 2HKO with Earth Power, and destroy everything else (it will need some residual damage if it's not running Psychic). Now, Rotom-H
would be almost a perfect fit since it covers RP Lando with ease, hard counter Genesect, is not Dugtrio bait and it's badass in general, however the fact that you don't carry a Spinner makes that impossible. You could, however, use Starmie over Keldeo
and gain the spinner you need, while not losing much (let's be honest, a +1 uninvested Hydro Pump is not doing much, it can't even 2HKO Jirachi for example, Icy Wind barely tickles Lati@s that can come in, Trick, Psyshock or set up their own CMs, and every Toxic / TWave user out there ruins badly the whole set).
Starmie @ Leftovers | Natural Cure
Timid | 252 HP / 24 Def / 8 SpA / 224 Spe
- Rapid Spin
Rotom-H @ Leftovers | Levitate
Calm | 248 HP / 8 Def / 252 SpD
- Volt Switch
- Pain Split
- Toxic / Will-O-Wisp
So let's take a step back and watch what the duo Starmie / Rotom-H does for your team: they form a FWG core with Breloom; they cover many dangerous threats like Keldeo, Gengar, Tentacruel and others for Starmie; Tornadus, Genesect, Special Landorus, Scizor for Rotom-H; and while not solving your weakness to Water attacks, they mitigate it somewhat since Starmie has sizable bulk and reliable recovery alongside good Speed to Recover in the face of things, and Muk is not going to take Hydro Pumps much better than Rotom-W anyway (Specs Politoed almost OHKOs...). You should take into consideration this "core" for your team, if you plan to try my suggestion, and cover the residual weaknesses with small changes in playtesting phase (for example, CM Latias can replace Garchomp, retaining a setup sweeper but solving Water spamming problems completely). I hope the rate was useful somewhat, I fee that it's definitely not one of my best so sorry if it doesn't Good luck!