>>44656199First fight with Ultra Necrozma in US. I hadn't played any game since BW2, and didn't spoil myself with game info, so it was a big surprise. I didn't know what type it was either.
Needless to say Necrozma just one shot every member of my party. They were slightly underleveled, but still. Did it pretty easy the second time, but yeah, that was the first time that my ass got handed to me by a fucking wild Pokemon when I had a fully healed team.
At second place I would put Steven from RS. Also went in without getting spoiled, so I had no idea what types Armaldo and Cradily were.
Maybe worth it to mention that I never use healing items in battles, even when I'm sure I can win with them.