Raid experience sharing
Just soloed a Donphan raid in Cloudy weather. I'm lucky the elephant doesn't acquire a Play Rough otherwise I will be beaten. My team matchup is a iv 87 Kyogre 3552 cp with 2 max-out double water Gyarados, 1 max-out exeggutor with BS/SB and 2 WG/HP vaporean (lv 40 and 39, iv > 90). I used the empty party trick so that I can enter the battle with 176s left (phone is old), and won it at the last second (literally). The charge move of the boss is earthquake, although not super-powerful but still dealt great damage on my kyogre, so I managed to dodge 2 of them to get 3 HP. Gyarados's Flying type makes it get less damage from the charge move, so I didn't dodge at all. It went smoothly that I just managed to use a HP at the last moment and beat it. Only first 3 mons were used.
To conclude, Donphan is still quite challenging for non-elite trainers (I mean trainers with no legendary army). With bad luck (glitchy or PR boss) it might be impossible to beat.
Answers
It killed first two of my mons (Kyogre first and 1st Gyarados), and almost killed my 2nd Gyarados before I beat it. That is actually my second try. On my first attempt I dodged too much with both Kyogre and Gyarados. The remaining HP of the boss is within a hit of Hydro Pump so I'm pretty confident I could beat it on my next attempt and I did make it.