Word to the wise, some characters die half way through the storyline so its technically pointless leveling them up as they won't save you on the final battles near the end which become difficult.
Not To Train:
This may sound simple but you would be surprized how many people miss an opportunity to do this.
First off in battles before you finish off the commander of the enemy forces or meet your objective you can use any skill slots you still have remaining. If your unit cannot use them on an enemy then just use a support skill on yourself or an ally. If an enemy is in range use whatever you want on the enemy. If they are low on hit points you could just use skills that diminish stats like defense or offense until you run out of skill slots. It's also best to take advantage of using your skills you are just learning, it will say the level of your skill when deciding which to use, so if you see LV 0 on any be sure to use them as much as possible.
Doing this will give you a chance to learn a lot of skills early in the game, giving you a chance to learn more advanced skills earlier in the game giving you a huge advantage.
If you find yourself in some trouble, say with only your commander left against 3 opposing units, don't fret because as long as you have some good Skills such as Fate or Transform your fine.
The lower your Unit Bar goes the faster your Skill Guage replenishes, so just run up to your opponents and attack using a skill and retreat away to a safe distance. Repeat until you have defeated the designated officer.
You can simply switch characters on your team by pressing the L2 button and then using the D-Pad to scroll through the list. This is a much shorter method to the Ordered List on the Start Menu and you don't have to wait for the pauses, its nonstop action this way!
Load your SW:XL Data from the planning screen while in a game and she will join your forces!
Simply have Samurai Warriors Data saved on your memory card, and load this data from the planning screen during your game. Keiji will automatically join your forces!