Not a threat by himself, HUGE HERMIT is here to slow your progress and prevent you from hitting the main boss of the stage, either being JUPITER KING or HI-DO.
Exploit this enemy's low range by using damaging cats and you won't have issues. Since this enemy attacks fast, however, you'll need a solid defence in order to keep it into place. This can be done by meatshields such as Tank Cat or Crazed Tank Cat.
Jamiera Cat is particularly effective against this enemy, he can tank HUGE HERMIT's hits well and can knock him back.