While one may think that choosing a party of five people from amongst 17 total characters might be difficult, it’s not that bad in Persona Q. Let’s get this straight right from the beginning; You can use any combination of the characters you want, as all of them can fulfill one of the roles needed to finish the game. Just know that some characters excel at those roles than others, which is why some people recommend them over anyone else.
Magic is not as good in this game as in other Persona titles, as the SP cost can be high and it’s definitely not as strong as physical attacks. That’s what your frontline characters should be focused on, with ideal characters being Kanji, Akihiko, Chie, Shinjiro and even someone like Aigis. Skills that hit multiple times are great, with such endgame skills being Myriad Arrows or Hassou Tobi (the latter being exclusive to Yoshitsune).
Status Ailments and Binds go a long way in this game, as there isn’t a single enemy in the entire game that is completely immune to every single ailment/bind, even the final boss! The best overall ailment to use is Panic, as it makes it so enemies only use regular physical attacks and nothing else. Poison also has its uses, especially in the beginning of the game, when some of the bosses/FOEs had a lot of HP.
All three of the binds are great, but they tend to have situational uses, especially in some of the later and harder fights. Almost anyone can be a great ailment/bind user, but someone who isn’t going to do much damage is going to be good at this, like P3MC or Naoto.
The best healer in the game is one who doesn’t even directly fight in battles, and that person is Fuuka. Healing Breeze will regen some health back at the end of each turn for a total of three turns. This skill gets an upgrade at level 50 with Healing Tide, which recovers more HP than Breeze. That said, it’s always good to have a backup healer in case you need it. Both Yukari and Yukiko learn healing skills, but know that they are a little slower than other characters, so you’ll have to compensate and think ahead.
Rei also learns a healing skill at level 3, but it only affects one row, instead of the whole party, like the Media line. In addition to regular healing, you want to make sure that you have the revive skill, called Recarm. Both Ken and Teddie learn these naturally but the latter is considered one of the worst characters in the game, so it might be easier to rely on the skill being on a Sub-Persona.
Linking is something that is a different beast altogether and has the potential to be the biggest damage dealer in the game. It involves all of the skills that has "Link" in their name. The first thing you should know is that the person who initiates the Link should have a few things, such as high strength and high agility. Potential Linkers might be able to use the stat-swapping accessories to switch stats, so you can concentrate on other roles for the standout characters.
The way Linking works is that you use a skill (ex. Flame Link) and the next attack after that in the same turn will trigger it to activate again. There are passive skills that add to the subsequent number of attacks that can occur, like Double Link or Infinite Link. The max number of follow-ups you can have is eight with Infinite Link, and multi-hit attacks like Myriad Arrows only count as a single attack. Skills that produce an additional attack, such as Death Chaser, will trigger the Link.
As for who makes a good Linker, you will need a few requirements, such as high AGI and high STR. If a character has one and not the other, you have skills like Dragon Cry or Bestial Roar, which allow that character to go before everyone if they use it. One natural candidate for a Linker is Akihiko, as he has great strength and agility without needing to use anything else. Aigis is another, but needs to switch her Endurance and Agility; the same applies to Shinjiro, Chie or Kanji.