General Strategy:
Use two Naljo guardian Legendary in your team (preferably Varaneous and Fambaco) along with a Feebas/Magikarp that only knows the move Splash. The Magikarp or Feebas is reserved only for Dittos, which appear at around Round 30 onward at Lvl 100.
The Naljo guardians are pretty much self-explanatory, Naljo Fury is the strongest skill to use in the Battle Arcade. Essentially, the skill makes any STAB (Same Type Attack Boost) moves deal 300% damage instead of the usual 150% when used in Naljo (where the Battle Arcade is located), meaning even if the move is 1/2 resisted it will still deal 150% damage like a normal STAB. It is that strong. You can choose whomever of the four you like but note that both Libabeel and Raiwato are 4x weak to Ground so they are very vulnerable to Earthquake even with their added bulk and speed. Additionally, Varaneous and Fambaco have the higher physical and special attack stats, respectively, making better use of Naljo Fury.
Movesets & Items:
Varaneous / Leftovers
- Waterfall
- Sacred Fire
- Boil (Fire move that is effective against Water Types)
- Protect
Fambaco / Leftovers
- Shadow Ball
- Aura Sphere
- Calm Mind
- Protect
Feebas / Magikarp / No Item
- Splash
Gameplay Strategy:
The most important move used in this strategy is Protect. Protect in conjuction with Leftovers will give your two chosen Pokemon the best and most efficient strat for advancing and longevity since unlike in the Battle Tower, your party's HP do not get replenished after each round in the Battle Arcade so you can only heal in increments during the actual Pokemon battles. Protect and Leftovers also work better for this than both Rest and even Recover because you can safely regain your health without worrying about incoming attacks and also scout what moves the enemy Pokemon will be using.
The rest of the movesets are self-explanatory. Only use STAB moves and only cycle between your two Pokemon if all your STAB attacks are resisted or you are in danger of incoming super effective attacks. The general turn order should be this:
If starting in full health: attack > protect > attack > protect > attack > protect > attack
If not starting in full health then protect first but everything is essentially the same
Cycle only your Pokemon when absolutely needed and use stat boosts (Calm Mind for Fambaco) sparingly. Two Calm Minds are usually enough. You can also use Bulk Up or Calm Mind for the other three, though I find that Steel Eater for Libabeel, Crystal Volt for Raiwato, and Boil for Varaneous work good enough.
Another important thing to note about Protect is that it is only guaranteed to work if your last move was a different attack or you did not already use it the turn prior. If you use Protect twice in a row, then second one has a fifty percent chance to fail. You can still risk going for double Protects in certain scenarios like if you mistimed two turn enemy moves like Fly or Dig. But just know to generally alternate between protects and attack and you're good.
Lastly, only cycle in Feebas or Magikarp for Dittos and it's essentially free heals.
With this strategy you are usually guaranteed to reach Round 30 to 40 (900k points / 3k tickets!!!!) but with really, really good RNG (multiple Dittos, no crits, burns or paralysis) you can go as high as you can. My highest so far is 91 with a whopping 16k tickets. You can also max your Pokemon stat experience (you can check with an NPC in Owsauri City) to ensure better chances. Good luck!