Shuckle gained a very fun trick in Alola with the addition of Z-Moves. Z-Power Trick for Trick Room.
Shuckle @ Psychium Z
Ability: Contrary
EVs: 252 HP, 252 Def, 4 Sp.Def
Relaxed nature (0, 1, 2, or 3 Speed IV)
- Power Trick
- Rock Slide
- Earthquake / Struggle Bug
- Protect / Struggle Bug
Z-Power Trick Shuckle, one of the most devastating Trick Room attackers in the doubles format. The idea is simple. Set up Z-Power Trick while the partner sets up Trick Room. Then, once Trick Room is up attack with a lot of power. Rock Slide is a given with STAB, not hitting the partner, and a lot of flinching with Shuckle being the slowest pokémon in the game. Earthquake is an option to get good coverage against most opponents that resist Rock Slide (like Steel types), although it does hit Shuckle's partner. Struggle Bug is an option in the opening if you want to stall out Fake Out and lower enemy offensive power, although it is expendable. Protect is valuable in doubles, but especially on Shuckle which is vulnerable to physical hits after Power Trick.
A Relaxed nature with maximum physical defence investment ensures Shuckle hits as hard as possible after Power Trick. Max HP investment is vital on any Shuckle to boost its otherwise pitiful HP and give it a big boost to its bulk. Due to rounding, the Speed IV can be anything from 0 to 3 and result in a ridiculously low speed stat of 9 at level 50. The small range of Speed IVs possible makes it a bit easier to breed for this. Contrary is the ability of choice as it allows Shuckle to benefit from enemy Intimidates which are common, boosting its attack stat. Even if it is hit by Icy Wind, Shuckle is so slow that it'll still be slower than minimum speed Stakataka at +1, so it'll still most likely be the slowest thing around. Contrary does not affect the +1 attack boost granted from Z-Power Trick, that stays a boost. Using a Z-Move for Power Trick has several benefits. It boosts Shuckle's attack more than a Life Orb would and allows Shuckle to set up Power Trick even when Taunted. It also prevents Whimsicott from Encoring it into Power Trick, as Encore fails if the last move of the target was a Z-Move.
Partners for Shuckle have to be considered well. They have to be able to set up Trick Room obviously, but aside from that there are several ones that come to mind:
Male Meowstic has Prankster, and can use both Quick Guard and Charm. With Prankster Quick Guard Meowstic can block any attack in the +3 priority bracket regardless of speed stats and/or the presence of Trick Room (most notably Fake Out, but also Comfey's Draining Kiss and Giga Drain), which other Quick Guard users cannot do. Prankster Charm allows Meowstic to give a boost to Shuckle right after it sets up, before it attacks, allowing Shuckle to go to +3 attack (775 attack at level 50 under Power Trick), or +4 attack in case of enemy Intimidate (930 attack at level 50), giving it ridiculous offensive power that sweeps games. Even in the presence of Psychic Terrain due to the common Tapu Lele, Meowstic can still Charm Shuckle since Psychic Terrain does not block priority moves aimed at allies.
Oranguru has Telepathy, allowing it to dodge Shuckle's Earthquakes. Oranguru can also block priority if you give it Psychic Terrain, and it can amplify Shuckle's destruction with Instruct.
Cresselia has Levitate, allowing it to dodge Shuckle's Earthquakes. Cresselia also has a lot of bulk and can somewhat amplify Shuckle's power with Helping Hand, although it has to rely on Ally Switch to help Shuckle dodge priority attacks.
Mesprit is an odd choice, but it has Levitate like Cresselia, can also Ally Switch, and gets Charm to boost Shuckle's power, although under Trick Room it will move after Shuckle (unlike Meowstic).
Xatu is in a similar boat to Mesprit, although it trades a bit of Mesprit's bulk for immunity to status moves like Taunt thanks to Magic Bounce. Xatu gets Feather Dance instead of Charm, which does the same thing.
Gothitelle is also an odd one. Although not immune to Earthquake, it does trap enemies, has acceptable bulk, and has access to Play Nice. Play Nice is a neat little trick that can boost Shuckle's attack stat while Shuckle uses Protect. Audino can also do this, although it lacks the trapping element Gothitelle has.