Thanks as usual!
Edit: my guess would be the "trap" is that if you forcibly lose and hand it off to the other team, you can make their captain answer (I was already imagining that like five chapters ago)--they don't get to pass it to the back in that case. If you do this 3 times and the captain passes, they have an inferior button presser and less knowledge for all of the later, harder questions.
However, this trap has a counter-trap, which is that the captain can get to 2 stars and then just say "I don't know" until question 19, at which point they can answer for real and win with a score of 1-0
I don't know if Sasajima will be willing to use that counter-trap--the "shounen manga" solution is to just believe in his team to qualify without him. But if it's Sasajima, he'll definitely know the answer to the 20th question, so the counter trap would definitely work if he chose to use it.
Actually, now that I think about it, Sasajima could even answer on question 18, and then the next Buzou buzzer could just use the same strategy to just force Planet's captain to answer 19 and 20. With only 2 right answers from the captain, Planet would automatically lose.