I've recently been attempting a nuzlocke of Pokémon: Soul Silver Version and this was one of the more emotional moments that happened. I made it to the Elite Four, beat them, and was battling Lance who was pretty tough but then I got in trouble when he sent out his Aerodactyl. My Feraligatr was weakened and I needed to heal up but if I did, the Aerodactyle would just damage me again and I wouldn't go anywhere. With a heavy heart, I ultimately decided that Chardonnay, my Dragonair would have to sacrifice itself so that I could heal Troy, my Feraligatr.

So, here is that moment where Chardonnay took one for the team, with a look of sorrow combined with a sense of knowing that this must be done as Troy watches on, crying out for this not to happen. (I shipped Chardonnay with Troy by the way.)

BTW: I did manage to defeat Lance because of this. Chardonnay was the only fatality of the Elite Four.