Leon takes the other guest characters to school, for sure. His damage output outclasses everyone else's, and you don't even have to train him (using FFII's wonky training system). He comes pre-trained.

Throw into that such facts as:

- His family ties to Maria
- Cool hair and armor
- A dark, brooding backstory (shades of FFIV anyone?)
- A name that's actually known and pronounceable (Firionia...Firionielia...what the)
- I'm saying it again cuz it's important: he can actually do damage.

Leon trumps the other guest characters, which is why he's the last to join and the only one to stay all the way through to the end.

I believe that wraps things up, yes?