This game is widely considered the hardest game in the series. It is said that the Belmont clan grows stronger with each new generation, and Trevor was the first to face Dracula (long before a parade of "the REAL first Belmont" Retcons started filing in), ergo the weakest Belmont to fight him.
It also makes sense in why he had help from Sypha, Grant, and Alucard, when most other Belmonts went solo when they fought Dracula. Back then, Dracula was too powerful to fight alone!
Made especially poignant considering in the timeline, this game is the sequel to Castlevania: Lament of Innocence, which took place over three centuries prior. It's outright stated by the narration at the end of that game that the Belmonts and Dracula would not meet again for quite some time. That's quite a lot of time for Dracula to gather power, even if he didn't outright start attacking humans until after the death of Lisa.
It's also worth mentioning that most of the times you face Dracula in other games, he's been resurrected prematurely before 100 years have been up and thus isn't completely at full strength. This game details his first death. No wonder it's hard, he's literally at the peak of his strength when fighting Trevor!
