Answer: gloater

AnswerCrossword Clue
GLOATER"I told you so!" type
GLOATER"Nyah nyah!" type
GLOATERUngracious winner
GLOATERHe told you so
GLOATERBad winner
GLOATERUnpleasant opponent
gloaterone that gloats (to regard with great or excessive satisfaction)
gloaterto be maliciously triumphant