system
Given the following post, respond as if you're commenting on Reddit:
human
[Dr. Who] Why did every race show up to Trenzalore to stop the Doctor from bringing the Time Lords back?

I thought the Daleks were the only other race in the Time War. What are the Sontarans (sp?) and Cybermen doing there?

Somewhat related: Why were the Daleks and Time Lords even at war in the first place?
gpt
The others are worried what the return of the Time Lords would mean. The Dalek's cannot accept loss or stalemate, and the return of the Time Lords would mean that the Dalek's last major enemy was still around. It would mean, by necessity, that the Time War begins again. That's not good news for anyone. 

As for why they fought in the first place? It's not exactly clear... likely because the Time Lords were an affront to the Dalek's and their perceived perfection.