For Zachary I was thinking a young adult/late teens voice with a hint of pride in every sentence. He's a pretty cocky guy. A North American accent would be favorable over any other.

Zachary is more experienced at missions than everyone else in his new team and feels as though there's a large weight on his back, always feeling pressured when he really isn't. Zachary comes off as friendly at first, but can actually be kind of a jerk. He loves to tease people and enjoys seeing them flustered. He deeply cares about his teammates, even though sometimes it may not seem like it. He gets angry easily, but is never really seen that sad.  His motives are unclear for some of the things he does, including his never ending fascination with Xander. His favorite teammate is Xander, and he can always be seen hanging around him.

He uses his ability armor to transform certain parts of his body or his whole body to resemble a dire wolf-like creature.