"Welcome, welcome," the alien says to both groups which are looking frantically for a way out, "it's great to have you both here today. You two groups of five are the lucky contestants of my interdimensional game show! Now for a brief rundown of the rules. Each of you will compete in a 1 on 1 challenge. The winner will earn their team a point. The first team to three points wins and gets to go back to their dimension. The losing team, however, will be stuck here in this dimension on the game show, who knows what kinds of things we could do."
They all want to object, they may not know the other group of people but they are all certain they don't deserve to be stuck here. There is nothing that they can do though, they want to get back to their home dimensions. If only there was a way for them all to make it out unharmed.
There could be a second chance for the other group if the alien continued their game show with other groups from other dimensions. Who knows what torture could wait for them if they lost? It was not a chance that any of them were willing to take.
The alien looks around at both groups. They would like to see some good competition, especially on the first airing of their game show, they wanted to be interesting. They match the pairs up in their head, perfect!