Recently, I've been playing drips and drabs of Valkyria Chronicles. Not long ago, I played lots and lots of Fire Emblem Awakening. Let's compare Valkyria Chronicles and Fire Emblem: there's a lot to be learned.
Valkyria Chronicles and Fire Emblem have comparable ratings (very high for a niche tactical game), but Fire Emblem made a huge splash while Valkyria Chronicles sank without a murmur. So sad. But they are games of similar quality - both have deep and interesting gameplay, both have a fairly decent story line, both have annoying, uninterruptable enemy turns that can last ten minutes...
And both are ensemble games.
In both cases, you pick around eight characters out of a massive bank. Fire Emblem has around 35 characters, while Valkyria Chronicles has at least 50 and probably more like 80. All of the characters are unique but scripted - that is, no random characters like you'd get from Final Fantasy Tactics.
In both cases, a major piece of annoyance is the same thing that gives the game their ensemble flavor. Choosing 8 out of 50 characters feels arbitrary and limited. Unless you're a power leveler, you're generally going to just have a dozen or so that are your "first tier" characters and ignore the rest. At least, that's the normal way to do it. But let's get into the nitty gritty details.
Valkyria Chronicles has waaaaay better character design than Fire Emblem. Although it has around twice as many characters, few of the characters feel like clones, repeats, or schtick characters.
In Fire Emblem, the characters always feel like schtick characters. They have a thing they do. They may have a personality behind that somewhere, but nearly everything is dominated by their schtick. For example, the dragon shapeshifter is theoretically a very interesting character with an interesting take on life... but her loli schtick is so heavy you rarely see it. Similarly, there's a candy-eating rogue, a clutzy knight, an overly rational mage woman, a yaoi-bait butler knight... most of the characters are built around a schtick first, and a character idea second.
It feels like they came up with a bunch of "adjective noun" character descriptions, handed them out to half a dozen character designers, and then just threw them in the game. Unfortunately, this resulted in a lot of the characters feeling very similar, because "clutzy busty knight", "obsessed busty knight", and "pet-obsessed busty knight" given to three different people are often going to come back as the same character three times.
In Valkyria Chronicles, on the other hand, the characters were clearly designed to feel distinct from each other. Valkyria Chronicles chose to design every character with an eye for what other characters there are, especially within their class. There's only a few characters that feel overly similar, and those are typically characters with completely different combat roles - there's a sniper and a machine gunner that have very similar character designs, but you're not going to confuse a sniper for a gunner.
Valkyria Chronicles' much stronger character design shines through even in a game where none of the characters are ever introduced. In Fire Emblem, every character has an introduction skit where you can get to know them a little. Valkyria Chronicles doesn't: they just show up in the list of hireable soldiers.
Still, Valkyria Chronicles' better character design is not necessarily a better approach.
Fire Emblem has a lot of character interaction - characters talking to other characters and so on. The schtick approach means that you'll always know precisely who is in the skit. "Oh, it's laughing evil mage and foppish archer guy". It also gives each character a clear line of interaction when the two core characters might not have anything particularly compelling to say to each other: "foppish archer guy gets creeped out by laughing evil mage! It's funny!"
Valkyria Chronicles took the opposite approach in that the character relationships are supposed to feel more... realistic. War stories are about camaraderie under fire. The relationships aren't typically very complex: there's only a few basic shapes they take. Character schticks are typically to add flavor to the relationship, rather than to define it. I think that's fine. In fact, it offers an advantage that Valkyria Chronicles didn't take advantage of: because the relationships are generic war story relationships, you could create friendships and bonds between any characters. Even though each character has a unique feel to them, their relationships are quite simple.
Valkyria Chronicles didn't do that, of course, which we'll get to in a minute.
One of the things Valkyria Chronicles did do, that I applaud them for, is that their characters aren't painfully boring. It's a standard of tactical games to make the main characters insaaaaaanely boring and safe. Fire Emblem did so: virtually all of the characters are boring and safe, certainly all the main ones are. In Valkyria Chronicles the main trio are pretty dull, I admit it. But the fourth and fifth members of the band are a dismissive career grunt and a classy racist. Both of these characters are grating but also appealing: even as they grind against the main characters' unfailing Jesus-like goodwill, they never feel like villains or bad characters because their flaws are offset by their very real character strengths. They feel like flawed, interesting characters and their collisions with the main characters add a lot of spice to the party dynamic without falling back on the tired meme of "secretly an evil spy" or whatever.
In Fire Emblem, this never would have happened. All the characters worship the main characters, they all get along perfectly, they all fit into the same group and feel like part of the same crowd. But in Valkyria Chronicles, you really feel that these people might be a good team, but they don't all fit into the same social group. Some are from different generations, have different interests, different social groups... it really gives a much stronger sense of a group being drawn together by circumstance and hard work, rather than fate just gathering up all the perfect people in the world and tossing them in a giant generic pot.
So, final thoughts on character design:
1) Design your characters to be distinct from each other, not just to have a distinct schtick. Even if you do schtick-based design, redesign characters that end up too similar. This means both visual design and personal characteristics.
2) Make flawed characters. We're not talking about tragic heroes that are undone by their own flaws, we're just talking about characters with some thorns. Make them prick the other characters from time to time. They need to have good traits, too: the player should never think they are beyond redemption or are awful people... but their prickles will make the party seem much more interesting and realistic, and also give them a good character arc.
3) Make characters that don't really have much in common a lot of the time. Not everyone needs to be 22-year-old highly energetic adventure-ho man. Look at the people who don't hang out with you: put them in your game and make it so they don't really hang out with you there, either. They're still team members and even friends, but if there's a vacation where you all go to the beach, not everyone is going to go swimming, not everyone is going to play volleyball.
Character Stat Design
Fire Emblem and Valkyria Chronicles both have excessive amounts of personal characteristics attached to their characters. But this is where Valkyria Chronicles falls short. While Valkyria Chronicles was better in terms of character design, it's a whole lot worse in terms of making them feel distinct statistically.
In Fire Emblem you grow into the character's distinct traits. Who they can get into relationships with, what classes they can change over to - these are often quite complex and specific, but they don't have any effect until you decide to develop them. They are uniquenesses that grow as the player wills.
In Valkyria Chronicles, the characters have friends and unique traits in a vaguely similar fashion, but they're mostly just BAM right up front. So you're suddenly faced with 50 unique characters, each of whom has 2-4 unique traits and 1-3 unique friendships and you're trying to select 20 of them and them winnow it down to 8 and... whew, the game just drowns you in uniqueness.
This is made worse because Valkyria Chronicles doesn't really have any directed character growth of any type. It doesn't matter whether you take someone into combat or not - everyone levels at the same rate no matter what. Even their personal traits are relatively minor - I frequently take people with severe allergies to the battlefield into battle, because the severe allergies do almost nothing. Of course, on the flipside, the advantages also rarely work, and rarely do much even if they do work. "Night vision" sounds like a great trait for a scout or sniper to have... but it only kicks in once every ten turns or so. How does that even work?
Well, either way, when it comes to creating unique character stats, I recommend taking after Fire Emblem, not Valkyria Chronicles. The player should be able to grow the characters' unique traits, both in terms of combat capability and in terms of relationships.
Also, I think it's worthwhile to have characters volunteer information about their specialties on the battle selection screen. When you highlight someone to add them to the battle, they should have a little passive dialog box that pops up and says "I can see in the dark, that's gonna be real handy in this battle!"
Another important feature is whether or not the player cycles the characters. In both Valkyria Chronicles and Fire Emblem, I typically settle on a few mains and then everyone else is left in the background. I think this is a real shame. It'd be worthwhile to have some character cycling impetus.
One small method of character cycling used in Fire Emblem is the buddy system. Because you're inevitably going to want to at least try to fill in the buddy list on your mains, you start to cycle people in so you can become buddies with them.
There are other ways, too. I like the idea of forcefully cycling characters. I think Valkyria Chronicles would be better if, instead of choosing 20 characters that you then choose 8 from, the 20 characters were randomly determined each time (with guaranteed ratios of class types).
Another option is the "everyone every round" method, where you can engage in any number of fights in a given story turn (week, day, month, whatever), but each character can only be in one fight. So if you have 50 characters, you might split them up into 8 different battles and fight each. The downside of this is that you may need to have some memory aids in place (such as sub-unit colors and extensive team chatter) or you'll start to lose track of the 50 characters.
I guess that's it.