You can easily check the base stats of each character under the "status" menu, in "tactics."
I'm currently playing through at level 13, so my stats may differ from yours; however, the base values for my current party are as follows:
Tiz:
Str 16
Vit 16
Int 15
Mnd 16
Dex 16
Agi 14
Agnes:
Str 14
Vit 14
Int 17
Mnd 17
Dex 14
Agi 13
Ringabel:
Str 15
vit 15
Int 16
Mnd 14
Dex 17
Agi 17
Edea:
Str 17
Vit 17
Int 14
Mnd 15
Dex 15
Agi 14
So as you can see, Edea is suited to be a fighter-type; Ringabel, to be a faster type, a la thief or ninja; Agnes is best as a mage; and Tiz is an all-rounder with slight leanings toward Mind-type or Strength-type jobs.
Edit to add:
However, the other poster IS indeed correct that the difference is pretty small, and mostly insignificant. As a minmaxer, though, the difference between 17 base Dex and 14 base Dex is pretty huge early in the game.
Best Answer
When you abililink with a bot or friend you gain their support abilities as long as you have the job asterisk that they have leveled up. These abililink abilities will be red in your abilities menu.
Note: KaruShale mentions in the same post that the color is yellow when they are abililink abilities, but from my experience with the EU version, it is red. Maybe it's different depending on the region?
I'll provide a more concrete source when I can.
Source: GameFAQs Forum Topic