withstander vs battler

withstander and battler both are nouns.

Word	Noun	Adjective	Verb	Adverb
withstander	Yes	No	No	No
battler	Yes	No	No	No

As nouns, battler is a hypernym of withstander; that is, battler is a word with a broader meaning than withstander:

Other hypernyms of withstander include belligerent, combatant, fighter, scrapper.

withstander (noun)	battler (noun)
an opponent who resists with force or resolution	someone who fights (or is fighting)
a fighter who holds out against attack