Tyson is Josh's best friend. We don't get to hear about his future (probably because Josh isn't as nosy about his friends as Emma is), but for the time being, his dad owns GoodTimez Pizza, a popular spot in town. Sadly, his mom is dead, though, and he goes to visit his mother's grave often.
Tyson is involved with Kellan, Emma's best friend. Although their relationship is full of breakups and makeups, Tyson tells Josh: "I would never want to Kellan to get hurt. Last time, I just wasn't ready" (49.34). Is it a rollercoaster with these two? Yup. But's it's a considerate rollercoaster, Shmoopers, which matters: Tyson isn't a jerk.
To this end, though Tyson busts on Josh from time to time, it's all in good fun. He likes to tease Josh and give him a hard time, especially about girls—at one point he tells Josh that it's his "dream to be the guy who's friends with the guy who's hooking up with [Sydney]" (49.28), though he wouldn't want to date her himself because "too many people talk about you" (49.30). Tyson's totally fine being the sidekick, which suggests he's just as laid back as his buddy, Josh.