The phrase “pulling out all the stops” means making every possible effort or using all available resources to achieve a particular goal. A synonym for this could be “going all out”. This implies putting in maximum effort and leaving no stone unturned. For example, “The team went all out in the final game of the season to secure the championship.”
Another synonym is “sparing no effort”. This emphasizes that no effort is being withheld and everything is being done to succeed. For instance, “She spared no effort in preparing for the exam and achieved excellent results.”
“leaving nothing to chance” is also a good synonym. It suggests that every possible measure is being taken to ensure success and no risks are being taken. For example, “The organizers left nothing to chance in planning the event and it went off without a hitch.”
All of these synonyms for “pulling out all the stops” convey the idea of intense dedication and determination to achieve a goal by using every means possible.