Here's a cute little thing I threw together in RPG Maker. Basically, all you do is select a game from the list and it'll present you with a randomized party that you can challenge yourself to use on your next playthrough of that game. It's a pretty simple program, but I thought it would be fun for anybody looking for a challenge.
As a side note, the dialogue when you select New Mystery of the Emblem may be a bit spoilery, so read at your own risk if you haven't played that one yet.
I chose not to include FE1 and FE3, opting for Shadow Dragon and New Mystery instead. FE2 and FE5 are not on the list since I have not played them yet. FE4 is not included since you pretty much are forced to use everyone in that game anyway.
Anyway, let me know what you all think about this. Hopefully it'll help spice up your next playthrough!
EDIT:
There is also some spoilery dialogue in the Radiant Dawn option as well, so watch out.
Also, you should download the RPG Maker VX Ace Runtime Package before getting this. It can be found here: http://www.rpgmakerweb.com/download/additional/run-time-packages
EDIT 8/18/15:
New Version!
- Radiant Dawn party is now the correct number of characters.
- Awakening now included! You can choose whether to include Spotpass characters, children characters (excluding Lucina), both, or neither!
Screenshots:
Also, for anyone interested, here are the scripts I used for this project, minus the ones I made myself.
FE Randomizer v1.2.zip