What's the Name of That Book??? discussion

This topic is about
Book of Names
SOLVED: Children's/YA
>
SOLVED. YA Sci-Fi/Fantasy series. Read in late 90s/early 2000s. Three teens from different worlds must get from the outer to the center ring (layer?) of the worlds. They use stones to give them special abilities. [s]
date
newest »

From what I recall, the three main characters are
- street-smart con artist (Zack?). He was hustling people on the street with cards when first introduced to him.
- a girl warrior from a medieval-type world (Rowan?)
- a boy (Pixel?) from a futuristic world that uses Virtual Reality exclusively instead of physically doing anything such as meeting with friends virtually or going outside. I think I remember his skin is blue?
I'm not 100% on the main character names, but those above keep popping up in my head.
Once, one of the kids used a stone that made them speak backwards while they used it. Another stone took all the vowels out of their speech. I can't remember what abilities it gave.