Sonic Team Racing Confuses Me

So as a fan of the franchise, I am always looking forward to another game that features the cast, but this time around I am at a loss as to explain the reasoning behind the 'team' formats. Don't get me wrong, Team Sonic and Team Dark make sense and the team idea still works from the Sonic Heroes range, but it's the other teams I have issues with.
 

First off, why are the Chao a racer as part of Amy's team? I mean, if it's just Cheese and it's friends racing cause Cream can't join the race then that's fine, but a little more explanation would work. Which brings me to my biggest team problem.

Anyone else disappointed that Silver's vehicle should have looked

more like a Back to the Future reference?

The new team of Blaze, Silver and Vector is where I really scratch my head. The thing is, why is Vector here instead of Team Chaotix? I mean, if Big and Amy are still Team Rose, then surely Vector and Espio would be Team Chaotix with either Charmy or another stand in perhaps (heck, Espio makes more sense since he and Silver have at least worked together before). I'm more then happy for Blaze and Silver to be in a team together (cause I'm a shipping idiot), but there were still other options from the Sonic franchise to pick from. Heck, here are two of my preferred choices:

Marine the Raccoon:

Being from Blazes own dimension, it makes sense that she would be much like a sidekick to Blaze. In fact, Blaze is considered to be the Sonic comparison to her world, so Marine then would be the Tails of that world. Many in the community have already done a Sonic Heroes style team of Blaze, Marine and Silver (a team which I too support), so it would only be fair to carry that on here. Characters like Marine don't get enough expansion and in group games like these it is the perfect opportunity to bring them in for such a chance (cause we know they'll never really get one outside of these group games). My guess is that her vehicle would be very much inspired like that of a metal pirate ship, thus explaining her position as 'Power'. Would also be a good time to expand on the powers she had shown at the end of Sonic Rush Adventure, which some have classified as 'Hydrokinesis' and would work well with Blaze's Pyrokinesis and Silver's Psychokinesis (Team Kinesis?).

Shade the Echidna:

Another Echidna and thus, another one who could fill the role of 'Power'. Much like Marine, she really was only ever given one real shot as a character in a game and this would be a perfect opportunity to be given another shot. Being from another dimension technically, she would suit the 'not from this world and time' theme that the group has. A redesigned outfit and look could help bring her back in, as well as adding to her story of what she has been doing since then (yes, I am aware of Penders and his thoughts on the Nocturnus Clan, but honestly, Shade as a character could easily be done up to be distant from any such controversy and thus, not be no problem for Sega what so ever). Certainly, she has been one of the most ignored characters lately (given that most people want to see Nack/Fang, Bean and Bark as a team being what they want to see as the next team), a revival as a group game character could be useful.

Again, just my opinion as to what they could have used, just as many others have their own. I'm still interested in the game and I'll follow it until release date, but I feel like Sega keeps missing the mark when it comes to such games (like, you almost had it and at the end you just missed it). Still looks fun though.