Hidden Conditions:
The “VIP” of this mission is Frieza so you have to keep him alive at all costs. To increase the chances of Goku transforming, defeat Piccolo and Vegeta first before Goku. Once Goku and Krillin arrives, defeat Krillin first to push Goku to transform to a Super Saiyan. Defeat him while in this form to get a higher rank.
You must to defeat Krillin within 5 minutes to push Goku to transform in Super Sayan. It's not Random and it would be nice if you could add that to this mission. ^^