Persona 5 Royal took the relatively easy Okumura boss and made it one of the most challenging tests in the entire game. It becomes one of the most frustrating experiences since the boss isn't exactly trying to take the player out, choosing instead to hold them up long enough so he doesn't have to fight.
Players have to prepare thoroughly for a fight that they most likely breezed through in the original title, dealing as much damage to as many enemies as possible in order to end the fight before time runs out. The fight's unique mechanics make it hard for players to adequately prepare for. Players need a full stock of both items and teammates that prey on Okumura's weaknesses.
Two Turn Minions
While the enemies are basically identical to those found in the previous version of the game, every wave of robots will now have to be cleared in less than two shots. This will ramp up the urgency, forcing players to carefully plan out every turn in order to inflict the maximum damage possible.
If the plan fails and even one robot is left standing, Okumura will reset the wave and force the team to try all over again. He'll do this as many times as it takes, trapping players who haven't properly stacked their team in a 30-minute build up to defeat.
Stall Tactics
Okumura's 30 minute time limit is actually a factor now that he's taken to repeating waves and actively trying to stall the team instead of defeating them. This is a unique strategy and one that players should prepare heavily for, unless they want to be shot out into space.
The time limit sneakily includes even the cutscenes as the fight progresses, just in case the Phantom Thieves find the unrelenting robots too easy. Every cutscene will have three or more scenes and really chip away at the timer, making the margin for error even smaller.
Haru & Morgana
The boss' daughter and her strange cat are two essential characters in taking down the Okumura boss. Haru is the daughter to Okumura's heartless father; she's the only character who can consistently damage the robots outside of the protagonist.
Morgana on the other hand will damage bots and provide a cure for the Hunger that the team are bound to fall victim to. Both will be the main attack force to back up the player and make sure none of the other team members slack in performance due to battle conditions.
Attack Types
All Gun, Psy, or Curse attacks will have to be planned out beforehand. These three types of attacks are what will get the player past the two turn waves. Ensuring the most offence is inflicted on his robotic minions is only half the battle, especially because weakening the defense is another key factor.
Using skills such as Dekaja and Marakunda effectively, the player can take down enemy defenses before delivering a final onslaught. This is the perfect time to use the Gun attacks, as Persona 5 Royal has made them super effective after a key weakness has been taken advantage of.
Billiards & Darts
Playing a lot of Billiards and Darts might not seem like hard work, but players will need to play both to maximize their chances of winning this boss fight. Boosting both technical attacks and the Baton Pass mechanic, both games will make the Okumura fight significantly easier.
Getting better won't be all fun and games though, Billiards requires the player to buy and read books to unlock trick shots that will improve their game much faster. Darts is where the real fun lies, increasing the Baton pass and sharpening the players aim at the same time.
More Weaknesses
While this fight in particular has become one of the most difficult and labor intensive fights in its Royal edition, some significant defensive holes have been left for the player to exploit. Presenting weaknesses to six elements that have a better than usual effect on the usually tank like enemies.
One the flip side of the coin, the team has to deal with significantly more heat coming back at them, especially when it's being dealt by four minions at the same time. Defensive plans should be in place, even though the main target of the boss is to stall out until the big bang.
Gang Fight
Dealing with physical attacks will be a big part of surviving the battle. This becomes apparent when all four robots will target the protagonist and combine damage that can easily take out the character. This will most likely be followed up with a sacrifice order for one unlucky bot that will cause further damage.
Nullifying or resisting this damage can make the whole experience a lot easier, not having to worry about constantly recovering from heavy shots. Once a target is picked, they won't change until the turn is over and any unprepared characters are taken out.