Light Blue - Ike: This is going to be the standard one, yes? If so, I think Ike should be the one. With him featuring in two of the Fire Emblem games and being a playable character in the new Super Smash game, I think having him on our standard layout would be the best choice. (Path of Radius / Radiant Dawn)
Probably yes, but the standard layout will be dark blue.
Navy - Fin: He plays in both Seisen no Keifu and Thracia 776 and is a very popular character. Also, he's one of the most useful characters in the latter game and plays a significant role in its story. (Thracia 776)
Nope. Hector it is, simply because I already have high-quality art for this one.
Cyan - Ephraim OR Eirika: I don't agree with the notion of using both of them. Not if all of the other layouts will use only one character. But the twins do make sense, so I'm definitely rooting for one of them. I prefer Ephraim myself. (The Sacred Stones)
Probably. I doubt I can find good art for both separately, but possible.
Green - Chiki: I really doubt I need to explain this one. If you think Fa and Myrrh are badass, you should definitely add Chiki to that list. And she's the first of the powerful Mamkutes. And no, Banetou doesn't count. (Ankoku Ryu to Hikari no Tsurugi)
Looked around, no good official art, not gonna work.
Red - Alvis: Probably one of the, if not the most popular Fire Emblem villain. Being a Seisen fanboy myself, I think Alvis is the best choice to represent FE4. He's in both generations and plays a significant role in the story. Plus, he's badass. (Seisen no Keifu)
No good-quality art.
Purple - Percival: Awesome character, best Paladin in Hard Mode and overall a popular character. Also imporant enough story-wise to warrant his own skin. (Fuuin no Tsurugi)
WE HAVE A PATTERN HERE! No good-quality art!
The newer games are where the characters are going to come from because that's where we can actually find quality, workable stuff.