Thought I'd try a simple breakdown of the character's keywords as requested earlier:
Ambra - Versatile/Healer: Healer is obvious, Versatile means that Ambra can switch between supporting/healing teammates and being a good damage dealer.
Attikus - Disruptor/Brawler: Brawler means it's a melee-focused character, very few (if any) ranged skills. Disruptor means he's geared towards getting into enemy lines and causing panic and damage.
Benedict - Mobile/Pusher: Mobile means Benedict has quicker movement than other characters, as well as having good vertical movement. Pusher means he is a character suited to being on the frontlines helping your minion-waves to get to their destination.
Boldur - Tank/Brawler: Again, Brawler means melee-focused. Tank means that Boldur can take a lot of damage and is suited to drawing enemy fire away from weaker teammates.
Caldarius - Mobile/Skirmisher: Another quick-moving and vertical-movement-capable character, but Skirmisher means he's suited to hit-and-run tactics and is unlikely to last in prolonged firefights. Pick what small goal you want to achieve, zip in, zip out.
Deande - Stealth/Assassin: Stealth means that Deande can turn invisible for short amounts of time, allowing her to sneak up on enemies or escape from a bad situation. Assassin means she's suited to quickly moving in and taking out a single target with high burst-damage before quickly getting away again due to a lower health total.
El Dragon - Agile/ Skirmisher: Despite his size, El Dragon is incredibly quick, especially with his Clothesline skill. He's also another character suited to hit-and-run tactics.
Galilea - Territorial/Brawler: Again, focuses on close combat. Territorial means that she can affect the area close to her to give her a combat advantage or to drive enemies away.
Ghalt - Controller/Disruptor: Another character who's good at creating chaos in groups of enemies. Controller means his skills negatively affect enemy characters' movement, through stunning or displacing them.
ISIC - Tank/Disruptor: Another character who's best used to get in to enemy lines and cause panic. Being a Tank, he's got the skills to block a lot of incoming damage whilst he does so.
Kelvin - Controller/Brawler: Kelvin can also affect enemy movement, primarily with stuns, but in contrast to Ghalt is focused on being up-close and personal.
Kleese - Territorial/Shielder: More area-affecting skills for this character, as he's Territorial. Shielder means he's capable of restoring friendly character's shields instead of restoring health.
Marquis - Territorial/Sniper: Marquis' skills focus on making a small area dangerous for enemy characters, either by slowing or damaging them. Sniper comes from his main weapon which allows for high damage at a long range.
Mellka - Agile/Assassin: Mellka's quick and her skills allow her to lunge forwards quickly or boost-jump upwards. She's also a character suited to taking down single targets quickly.
Miko - Combat/Healer: Unlike Ambra's support style of holding back to lay orbs, Miko is best suited to fighting alongside teammates as the healing abilities are all fairly close range. Miko can also put out a fair amount of damage if healing isn't required.
Montana - Controller/Initiator: Can slow and stun enemies to impede their movement. Initiator means that Montana should be used to start fights thanks to his high damage output and ability to take damage too.
Orendi - Agile/Skirmisher: Another character that's quick on their feet, with the ability to bounce out of combat. Should be used for hit-and-run high ranged damage.
Oscar Mike - Versatile/Pusher: Can work with different approaches, such as head-on assault or using his invisibility to flank the enemy lines and attack from behind. As a Pusher, he's another character best used to keep your frontline moving forward.
Phoebe - Brawler/Assassin: Phoebe is good for dashing in at speed, taking out a target or two at close range, then dashing out again to recover for a further attack.
Rath - Agile/Assassin: Rath can move quickly and can gain the ability to double-jump, allowing him to reach his target in a very short amount of time. Again; high burst-damage output, but a bit more able to stay engaged thanks to HP-stealing.
Reyna - Rescuer/Shielder: Reyna is good for getting people out of sticky situations. As well as personal shield boosting, she can create an area-shield and make her shield-boosts restore a small amount of health.
Shayne & Aurox - Stealth/Initiator: Can turn invisible and should use that to shock-attack the enemy and take them out quickly.
Thorn - Agile/Sniper: Another quick-traversal character, but this time suited to moving out of harm's way and attacking from a distance.
Toby - Adorable/Territorial: LOOK AT HIM, HE'S A TINY PENGUIN. His skills are good at keeping enemy characters away from a designated area. Not quite so good at being on the frontlines.
Whiskey Foxtrot - Versatile/Assassin: Works well with taking out single targets, but can also be used well as a defensive character.