Sorry if this is common knowledge or whatever, but is there character customization in the DS versions of the game? If so, to what extent?
Sadly, no character customization other than the leveling up. When you gain an experience point, you can choose what to spend it on: depending on the character - strength, skill, endurance, or firepower. However, once you've reached the maximum of level 20, whatever stats you have by then, that's it. Try to keep your stats constant and equal. I didn't with Prime, and now he's got huge strength but half endurance.
Aw... that sucks. Well, I guess that's the trade-off for having so many more characters than the consoles.