Charon121: So I've started MM8 and got off the first island. However, I can't reconcile my usual RPG playstyle with the interchangeable party system. My party members will always have wildly different character levels, so their usefulness in battle will never approach equality with other party members. Furthermore, why should I invest money and time into training/promoting a character when there's always a chance I'll replace him/her with a better character tomorrow? Do I have to repeat the promotion quest in that case?
How do you guys play MM8? Do you decide on a fixed party and then stop recruiting new characters once you achieve the desired party composition? Or are characters meant to come and go, and anything else is just sticking stubbornly to RPG traditions?
Three things to note:
1) Most potential party members will not join you until your main character is about their level. So you can't get the level 50 Troll to join your level 10 PC (they'll generally say something like "you simply aren't up to the level of challenge that would interest me, and I'm not interested in following dead weight around"). There are a few exceptions, where the character won't join you until you complete a certain quest (which quest depends on the particular recruit); you can get some of these quite early if you know what to do, and speed runs rely on getting some of these level 50s while you are still single digit or early teens in levels. Yes, this does exactly what you would expect to the challenge curve of the game.
2) The higher level recruits will have spent some of their skill points. They'll usually have points spent in several of their "main" skills (like the necromancers will have advanced their various magics), but often points are wasted in other skills too (like having points in both dagger and staff). They also may already have expert/master/GM in those skills, if enough points are present. The higher level recruits will tend to already be promoted, as well.
3) Once you've completed the quest that allows for a promotion, you can later take anyone that isn't promoted back to the promoter and get the other characters promoted too. For example, once you've completed the Knight promotion quest, later you can bring any unpromoted knights and get them promoted instantly (no need to repeat the quest). The only possible exception would be Necromancer -> Lich; I don't remember whether you need to first acquire lich jars for them before the guy will go ahead and promote them (I don't remember if individual Lich Jars are even a thing in this game).
With all that in mind, I usually take the first recruit of each class that I want for my final party and use them. For example, if I want a necromancer, vampire, cleric, and knight, then I'll take the 4 characters you find on Dagger Wound and I'll use them for the rest of the game. They'll grow in power along with your PC, and you can spend their skill points however you wish without any waste. I'll recruit everyone else I can and leave them in the Adventurer's Inn, holding excess gear. That way I'm not filling my primary party's inventory with things like excess alchemy ingredients or equipment that I'm only going to pull out to pass the stat challenge pedestals.
I will note that I've never sat down and crunched the numbers on whether the higher level characters have more/fewer stat/skill points than the lower level recruits (once they are equal in level).
I will also note that due to the possibility of swapping out characters, all one-time-use permanent stat boosts (like barrels of colored liquid) only ever go to my PC in this game. Yes, my troll is drinking the +Int and +Pers barrels too. Smartest troll you'll ever see!
It is basically up to you whether you want to swap people out for others that you find. Do it as you see fit, since you are the Hero of Jadame!