The problem with Muk is the fact that Ludicolo doesn't have to Rain Dance as you switch in. If it just uses Surf you will take:
252SpAtk Life Orb
Ludicolo (+SAtk)
Surf vs 252HP/252SpDef Leftovers
Muk (+SpDef): 29% - 35% (124 - 147 HP). Guaranteed 4HKO.
That basically means Muk will take 58% minimum from Stealth Rocks + 2 Surfs + 2 turns of Leftovers. That means it will have 52% if it protects against Swanna AT BEST, meaning Swanna only needs an average roll to finish Muk:
4Atk Life Orb
Swanna (Neutral)
Brave Bird vs 252HP/0Def Leftovers
Muk (Neutral): 45% - 54% (190 - 225 HP). Guaranteed 3HKO. 4% chance to 2HKO with Leftovers.
Of course, if Ludicolo rolls more than minimum damage the chance of Muk dying increases exponentially. You could argue with Muk being able to Protect on the second Surf from Ludicolo, but as far as I know perfect prediction is assumed, which means Ludi could use that turn to set up a Rain Dance, eliminating your chances completely. Basically, as long as the core rolls average damage, Muk does not beat it.
(F) @ Leftovers
Trait: Own Tempo
EVs: 252 HP / 4 Def / 252 SDef
Careful Nature (+SDef, -SAtk)
- Wish
- Protect
- Toxic
- Return
Even with Stealth Rocks on the field, Lickilicky can effortlessly switch into any attack the core can throw at it, use Wish + Protect to stay healthy and Toxic + Return to wear Swanna and Ludicolo down. Even with Roost, Swanna won't be able to survive long against the barrage of Toxic and Return.
252SpAtk Life Orb
Ludicolo (+SAtk)
Surf in Rain vs 252HP/252SpDef Leftovers
Lickilicky (+SpDef): 45% - 53% (192 - 228 HP). Guaranteed 3HKO. 2% chance to 2HKO with Leftovers.
If Ludicolo Rain Dances as Lickilicky comes in, then Licki can just Protect to negate the damage SR caused on the switch-in. After that Lickilicky can Wish and either use Toxic (if Ludicolo didn't roll max damage) or Protect (if he did roll max damage). Once the rain runs out, Lickilicky is pretty much invincible while Toxic + Life Orb recoil will quickly wear away at Ludicolo:
252SpAtk Life Orb
Ludicolo (+SAtk)
Surf vs 252HP/252SpDef Leftovers
Lickilicky (+SpDef): 30% - 36% (130 - 153 HP). Guaranteed 4HKO.
Swanna faces pretty much the same fate, being unable to 2HKO Lickilicky with any of its moves. Since Hydration is unreleased, it won't be able to cure itself from Toxic and will slowly succumb to it, even with Roost:
252SpAtk Life Orb
Swanna (Neutral)
Surf vs 252HP/252SpDef Leftovers
Lickilicky (+SpDef): 26% - 32% (114 - 136 HP). Guaranteed 4HKO.
252SpAtk Life Orb
Swanna (Neutral)
Surf in Rain vs 252HP/252SpDef Leftovers
Lickilicky (+SpDef): 40% - 47% (171 - 202 HP). Guaranteed 3HKO.
4Atk Life Orb
Swanna (Neutral)
Brave Bird vs 252HP/0Def Leftovers
Lickilicky (Neutral): 37% - 43% (157 - 186 HP). Guaranteed 3HKO.
252SpAtk Life Orb
Swanna (Neutral)
Hurricane vs 252HP/252SpDef Leftovers
Lickilicky (+SpDef): 33% - 40% (144 - 171 HP). Guaranteed 3HKO.
The only way Lickilicky can lose is if it misplays or gets crit; even a crit doesn't mean certain death though, since Wish + Protect should be used every possible turn once the opponent is poisoned. I guess confusion from Hurricane could
technically beat Lickilicky, but considering the fact that Hurricane needs rain to hit every time (which Swanna can't even set up itself), it's very unlikely.