@Kerkovian you should see Cynthia in BDSP.
Competitive movesets
EV's
Beneficial natures
They buffed the shit outta her in the remake
Yeah I know. I didn't play it but saw several playthroughs and that fight was always dreaded like the Ultra Necrozma one.
I have similar experience with Pokemon Reborn and that Garchomp fight in the mountain. You'd know if you have played it and don't want to spoil you but you face a villian before your 4th batch or something and the villians pokemon is Level 75. I had to breed a ratata with quick attack and find a focus sash. Then use endeavour and quick attack.
Another time I used three pokemons with intimidate and switched on gyarados everytime it used earthquake. This fight and several other fights in reborn is why I haven't finished it despite 4 years of playing.