It seems that almost all of the 'mystery partners' or 'mystery heels' are decided upon at the last minute – and certainly long after the commencement of the angle in question. Eg – Hogan as the third man, the Black Scorpion,
the Higher Power etc.
Has there ever been a 'mystery partner' (or 'masked villain') that ended up being (a) a genuine surprise (b) got a great reaction and (c) was actually part of the initial plan?
About the only ones I can think of that MIGHT qualify is Ricky Steamboat as Eddie Gilbert's partner at the start of his 1989 NWA run… and Dean Malenko disguising himself as Ciclope in the Cruiserweight battle royale.
Rick Rude as the payoff for the Shane Douglas angle in ECW was pretty badass.