All the classes are very balanced out, it really just depends on your team and the ninjas you have.
People said he's not good for late game? LOL not sure where you heard that from ;P

If you want an advice on what class to switch to, i suggest switching to one with a different strength,
with lightning and wind being high damage cauing classes
fire and water for condition causing
and earth for defense.

I have a thread with mid/late game team recommendations,
you can take a look if you'd like to get an idea of how they battle, their strengths and weaknesses
team recs

No problem!
Well, I would suggest either the fire class or the water class c;
fun classes to play with
earth and wind are harder to form teams with

you c*so change to a different class again at lvl 66, 72 and 78 which allow you to unlock all of the classes

for lightning, you just need to have a good team, although defense/resistance/lp are his weaknesses, lightning is definitely the class that causes the highest damage, so you just have to defeat your enemies fast before they can get to you;P