'Polukus' is predominantly used in my R2 copy for N64, but in at least one instance his name was spelled 'Polokus'. I'm don't know about the spelling in other story mode varieties, so is it Polokus or Polukus?
Heh, like on the box of Rayman: Hoodlums' Revenge. Proper English says it is Hoodlums' instead of Hoodlum's as they spell it. Typography is everywhere, including Windows XP help files. (Because it is Windows--I've never seen a typo in any Apple-produced document for the Mac OS X 10.3 system.)
Polokus seems canonical. The team working on the N64 port probably mistook Polokus as Polukus, since every other version says Polokus.