There's actually a way to "kill" Krystal in Star Fox Assault by making her fall off a cliff using a glitch. I would make a video about it, but it's late at night and I can't record my shitty tv very well. Instead, I will walk you through how to pull off the glitch.
Step 1: Go into story mode and pick the map Sauria on the easiest level difficulty. You can do this on any difficulty, but it's just easier on easy level difficulty since there's less monsters.
Step 2: Get into your landmaster and then go to where Krystal is located. Kill all the monsters in Krystal's area and then she will follow you.
Step 3: Either push her off of the highest floor using the landmaster or have her jump onto the land master and then drive off of the highest floor.
Step 4: Now she will be on the lower floor and will be walking around circles trying to get back to the top floor due to her programming. Follow her around, and make sure to kill any enemies who are trying to get to you.
Step 5: When she gets close to the waterfall which leads to going off the map, push her using your land master. Using this method, it is possible to push her off the edge of the map, hence killing Krystal.
Congratulations! You have killed Krystal!
- Written by "aTwerkingPikachu
(this is just in case my reddit account gets banned in the future)