A big component of doing good in vex is having roles for everybody. I would recommend (if u have 6 people) to have 1 lead/floater, 3 builders, and 2 coders. Right now, having two coders might seem excessive but as vex has developed, the importance of code has become more and more apparent.
The robot that you are talking about is a traybot (I don’t know if anyone has said this, I’m responding blind). It’s a really popular design among teams (I built one and am rebuilding now.) so I’d say that I know a lot. One of the problems many people have with trays is that the the rollers commonly get pushed out under the weight of the cubes.
Important thread to read:
On the tilting mechanism, you need a 1:7 ratio (torque) with a 100 rpm motor (assuming no extra motors). Also, add lots of those rubber panels to the rollers for traction.
Some of the important robots so far this year:
42700N; Usagi; first tray lift
448X Ri3D; The original traybot
*This isn’t me saying these are the only good robots this year. There are plenty of others, but this is just off the top of my head.