The Champions Trophy.
'Champions' of what? Heck, since a rainy evening at Lords last summer, England aren't even champions of Europe.
I suppose you could get all semantic, and say that they are playing for the trophy that currently belongs to the present champions, but if that's the case, then who decided who the original champions were?
Furthermore, in that scenario, 'Champions' needs an apostrophe.
'The Apos Trophy'
Sorry - I'll get my coat...