Despite its versatile moveset, Donphan does have some key weaknesses that Pokémon Scarlet and Violet players can take advantage of. For one, its poor base 50 Speed results in it going second against most other Pokémon. Access to the Sturdy ability guarantees that Donphan will get to do something but it isn’t uncommon for it to fall in two hits.
The real weakness of Donphan in Pokémon Scarlet and Violet though is its Special Defense. With just 60 Special Defense, Donphan cannot take hits from strong Special Attackers. This is particularly easy to take advantage of due to its low Speed and 2x weakness to Grass, Ice, and Water. All three of these types consist of primarily special attackers so there are a lot of counters to pick from.
Pokémon Scarlet and Pokémon Violet can be purchased on the Nintendo Store.