Canada: The anti-replacement party is made up of replacements
(media.scored.co)
Honestly a good litmus test for how legitimate an opposition party is, is how much they attempt to be "big tent" (IE, wooing the opposition by adopting their position) and how firmly they oppose modernity. Hitler talked about the Big Tent Phenomenon in Mein Kampf, where seemingly Nationalist parties would immediately abandon any pretense of Nationalism just to remain in power because the leadership only cared about cushy state pensions rather than actual societal change.