The rules of this challenge are to defeat Launch Octopus with as few hits and the fastest time as possible, number of hits taking priority for ranking. Time begins when the bolt to the door shuts (indicated by the in-game sound effect, which you cannot hear well in this video, but it fires at 3 seconds in to the video.) and ends when Launch Octopus begins to explode.

For this challenge, the use of armor and health upgrades or subtanks is forbidden. The only special weapon allowed is the Chameleon Sting, but I did not use that.

This is a clear with no damage and a time of 0:44.