Complex sentence: Gonzalez lost to The Undertaker at WrestleMania IX by disqualification after he knocked Undertaker unconscious using chloroform this remains the only occasion that the Undertaker has not had a decisive victory in his 19 WrestleMania matches.
Split into simpler sentences: Gonzalez lost to The Undertaker at WrestleMania IX by disqualification after he knocked Undertaker unconscious using chloroform. This remains the only instance where the Undertaker has not had a decisive victory in his 19 WrestleMania matches.