Fire Emblem is a difficult series, I don't know if you guys have heard

[Words Of Wisdom]

Dante G said:
I haven't played Radiant Dawn yet, but I have a question. Is the leveling system like Path of radiance where you get extra xp and then use that to level up characters or do you have some kind of catch up battles to level up your weaklings?

Yes, you gain BEXP during the game however, unlike PoR, Radiant Dawn's BEXP gives a fixed number of +'s per level (3). 

This means that it's awful for normal level-ups (1-15) but excellent late tier (15-20) because you're guaranteed to get that 3 and can use this to max out your stats with weaker growth (which would otherwise not likely gain +'s from real levels).