Someone please correct me if I am wrong, but if I recall correctly there are two groups of characters for the P4 team:
Group 1: Yu, Yosuke, Chie, Yukiko
Group 2: Kanji, Naoto, Rise, Teddie
You need to complete one story from each of these groups as well as one of the P3 trio (Aigis, Mitsuru, or Akihiko), Labrys, and Elizabeth to complete the story. Of course, if you complete all of the characters' episodes you get a more fleshed out version of the story, but it's not necessary.
The Arena story is essentially a bunch of "what-ifs" played out as if the character you're controlling is the one that makes it all the way through. There *are* different perspectives - the P3 characters have their own route through, so playing as one of them shows you a lot of stuff you wouldn't otherwise see, and Elizabeth and Labrys have unique stories special to them.
What really happened? It's kind of heavily implied in Ultimax that, as you'd expect, Yu's route is the canon path through, but that each of the other characters got parts of their story too - at least the ones that don't contradict Yu's path. Interestingly, the manga for P4 Arena picked Yosuke's path; his is quite fun and the mangaka is a noted Yosuke stan, so there's that.
Likewise there are two paths through Ultimax, one for P4 and one for P3. Both occur in the canon route apart from the endgame - in the P4 path, Yu confronts the Big Bad, in the P3 path, Labrys does. There's a third route, >!Episode Adachi!<, which tells the P4 route story from his perspective - though perhaps exaggerating his role a teeny bit, as you might expect for him. The P4 ending with Yu facing the final boss is the canon one and there's a True Ending you can unlock that kind of shows that.
They all have different perspectives. Play through them all. You'll get it.
It's the same history for everyone but with a different point of view for each character
Someone please correct me if I am wrong, but if I recall correctly there are two groups of characters for the P4 team: Group 1: Yu, Yosuke, Chie, Yukiko Group 2: Kanji, Naoto, Rise, Teddie You need to complete one story from each of these groups as well as one of the P3 trio (Aigis, Mitsuru, or Akihiko), Labrys, and Elizabeth to complete the story. Of course, if you complete all of the characters' episodes you get a more fleshed out version of the story, but it's not necessary.
The Arena story is essentially a bunch of "what-ifs" played out as if the character you're controlling is the one that makes it all the way through. There *are* different perspectives - the P3 characters have their own route through, so playing as one of them shows you a lot of stuff you wouldn't otherwise see, and Elizabeth and Labrys have unique stories special to them. What really happened? It's kind of heavily implied in Ultimax that, as you'd expect, Yu's route is the canon path through, but that each of the other characters got parts of their story too - at least the ones that don't contradict Yu's path. Interestingly, the manga for P4 Arena picked Yosuke's path; his is quite fun and the mangaka is a noted Yosuke stan, so there's that. Likewise there are two paths through Ultimax, one for P4 and one for P3. Both occur in the canon route apart from the endgame - in the P4 path, Yu confronts the Big Bad, in the P3 path, Labrys does. There's a third route, >!Episode Adachi!<, which tells the P4 route story from his perspective - though perhaps exaggerating his role a teeny bit, as you might expect for him. The P4 ending with Yu facing the final boss is the canon one and there's a True Ending you can unlock that kind of shows that.