The phrase "pitted oneself against" is commonly used to describe a situation where someone has deliberately challenged or competed against another person, entity or idea. However, there are several antonyms that can be used to convey the opposite meaning. For instance, 'collaborated with' or 'assisted' can express cooperation rather than competition or opposition. 'Aligned with', 'supported' or 'joined forces with' suggests working together towards a shared goal. In contrast, 'avoided', 'ignored', 'disengaged', or 'bypassed' all convey a lack of interest or willingness to engage with a particular person, entity or idea. Using appropriate antonyms can help to clarify the underlying meaning and intention behind an action or behavior.