Moves
Fake Out buys a turn of momentum for Togedemaru's partner and can often be used to ensure its partner is able to set up Trick Room. Endeavor allows Togedemaru to whittle a target's HP down to near-zero, softening it up to be KOed by Togedemaru's partner. Encore is mostly just a filler move, as Togedemaru should be using Endeavor most of the time, but Encore can be used to lock a target into a passive move such as Protect, thereby allowing Togedemaru and its partner to focus on the other enemy slot. Spiky Shield is used to protect Togedemaru from an incoming attack for a turn so its partner can deal with Togedemaru's threats or get into a better position. Spiky Shield is preferred over Protect for its added ability to inflict chip damage to foes that use contact attacks.
Set Details
At Level 1, Togedemaru's EVs and IVs have no effect on any relevant stats other than its Speed. The given set uses 0 IVs in Speed to drop the stat by one point, ensuring that Togedemaru moves first inside of Trick Room. Berry Juice, when used in tandem with Togedemaru's low HP stat and its Sturdy ability, ensures that Togedemaru will always recover to 100% HP after taking its first hit. In essence, Berry Juice ensures that Togedemaru needs to be attacked three times in order to be KOed. Shell Bell, on the other hand, when used in tandem with Togedemaru's low HP stat and its Sturdy ability, allows Togedemaru to recover to 100% HP every time it uses Endeavor on a healthy target, essentially creating an endless loop of recovery until the opponent is able to double target Togedemaru.
Usage Tips
Togedemaru can easily be KOed by double targeting, especially before Trick Room is set, so it is crucial to protect or switch out Togedemaru on turns where its partner can't deal with at least one of the opposing Pokemon. Outside of Trick Room, Togedemaru can provide Fake Out support to allow a partner to set up Trick Room. However, it needs to be wary of faster Fake Out users like Incineroar and Mew as well as Tapu Lele, which can block Fake Out with Psychic Surge.
Inside of Trick Room, Togedemaru's general strategy is to use Endeavor on a target, bringing them into KO range for Togedemaru's partner. Be wary of targets holding a pinch Berry, such as Tapu Fini with Wiki Berry and Incineroar with Figy Berry; targeting these Pokemon with Endeavor will only drop them to 50% HP after the berry activates, which may not be low enough for Togedemaru's partner to score a KO. It is also worth emphasizing that Togedemaru is incapable of finishing off a foe due to its weak Level 1 stats (aside from using Fake Out on a target with 1 HP), so it always will rely on its partner to score the finishing blows.
Togedemaru's item of choice has implications on how it should be played. Berry Juice makes Togedemaru a bit more forgiving to play, as it can survive one turn of double targeting; for example, Togedemaru can switch into an attack on Turn 1, use Fake Out on Turn 2 to support a Trick Room setup, and still be alive on Turn 3 to get off an Endeavor. Shell Bell, on the other hand, makes Togedemaru less forgiving to play outside of Trick Room but makes Togedemaru considerably harder to KO inside of Trick Room, as it can continuously recover to 100% HP.
Team Options
Togedemaru requires Trick Room to be effective, so it should be accompanied by Trick Room setters like Stakataka and Diancie. Stakataka has notably great synergy with Togedemaru, as it can activate its Beast Boost ability repeatedly by picking off the targets that Togedemaru whittles down with Endeavor. Hoopa-U is also a great partner for Togedemaru, as it can dissuade foes from stalling out Togedemaru's Endeavor attacks with Protect. Other low-speed Trick Room attackers such as Mega Camerupt and Lurantis also work well with Togedemaru, as they generally move before their foes inside of Trick Room and can finalize the KO on targets that have been weakened by Endeavor. Priority attackers, such as Extreme Speed Zygarde and Bullet Punch Scizor, can situationally make Togedemaru a threat even outside of Trick Room by threatening to finish off an Endeavor-weakened target while Togedemaru attacks the other foe with another Endeavor.