So, let's take the Saiyans out of the equation. This is the team at their current and/or prime levels (whichever one is highest), including the current Super manga. The line-up is as follows:
Piccolo
Android 17
Android 18
Yamcha
Tien
Chaozu
Krillin
Roshi
Good Buu (optional)
Round 1: Who is the most powerful single foe that they can beat? Who's the weakest that beats them?
Round 2: What is the most powerful established team (any genre) that they can beat? Likewise, the weakest team that beats them?
Standard Khazan arena rules apply.