One thing you can do is go into the free battles (outside of the campaign) and look at the units for the factions, including what their walls do, but it’s a lot to figure out at first.
Heh, in that boss battle you mentioned, I didn’t suffer a scratch thanks to prodigious use of unicorn troops. They might be a tad bit overpowered. As you said, there are some creative battles where you have to do things like hit targets that move each turn.
Not sure if you’re in the second chapter yet, but the difficulty has really ramped up. I keep wanting to do some of the side stuff and getting slaughtered. Some of the puzzle battles are downright devious, and I think of myself as pretty good at that sort of thing.
As Mark Bozon said at IGN, I’d also very much like to have been able to see what level an opponent was before a fight started (this really begins to matter in the second chapter). I’d love to tell you how long I’ve played, but the timer runs when the DS is asleep.