Possibilities:
The movie is continuity-screwy and just ignores the driver issue
They start of sharing a driver but Sento makes him a new one so they don't have to bicker over it.

I'm going to say the latter is most likely. I mean, it's not like Sento hasn't already demonstrated a clear working knowledge of Full Bottle based tech.

Good shots at MerryChristmas Best Match.

So far I am enjoying Build as the same as Ex-Aid. Would be interesting to see how it evolves.

Quick warning btw, this thread WILL post spoilers should we come across them, especially leaked forms. You ok with that? Don't want someone to get spoiled by accident

Japan sure loves strawberry cakes for Christmas. I don't know if it is still a thing but I heard once Japanese people would always eat strawberry cake and KFC(yes, THE KFC) when it became Christmas.

Kamen Rider Build TanteiTank Form:

http://www.tokunation.com/attachment...1&d=1509670536

Kamen Rider Build DoctorTank Form:

http://www.tokunation.com/attachment...1&d=1509670536

Kamen Rider Build OrangeMedal Form:

http://www.tokunation.com/attachment...1&d=1509670536

It's a dog! It's a mic! Actually, it's the yearly toy bundled with the opening theme's cd and such.

RabbitUSB Form

EDIT :

TanteiGame Form

DoctorUSB Form

Wait, so they have special costume halves for the Legend bottles when build makes a Trial Form.

So why not just make the Legend Rider's Best Match be the two halves together instead of Build just wearing the rider's suit?