>>56504380>>56504891This was a stylistic thing that changed over the years. RBY uses die/killed mostly in reference to Rocket and Lavender town.
Meanwhile, Emerald doesn't use the words at all except this reference in Parasect's dex entry.
>PARASECT are known to infest the roots of large trees en masse and drain nutrients. When an infested tree dies, they move onto another tree all at once. I haven't played the newer games but judging by examples posted they're a bit more cavalier about using the words.
If you're seeking to maintain the tone of the games it's probably fine to use the words in passing or in reference to past events, but I think an explicit threat like "Us at TEAM XYZ will kill you for meddling in our work!" would seem a bit out of place.