The final boss of RE4 , Sadler,is so easy.

[Anfebious]

Player2 said:

The_Sony_Girl1 said:

All I did was throw grenades at him. Then Ada gave me the rocket launcher and itkilled him. I had a harder time with Chief Mendez and Salazar.

That works for Mendez too. Well, almost every boss in  RE 4 can be stunned by regular or flame grenades, leaving them open for easy magnum shoots.

Exactly this. Any boss in RE is super weak to the magnum. Just save those bullets and waste them away on the bosses.