Why are the BC Liberals supported by the Federal Tories? Is BC that much more left-leaning than the rest of Canada?
Also why is Saskatchewan the only province that has just two parties?
The BC Liberals are a purely center-right party. They are significantly to the right of the federal Liberals, though some more center-to-center-right federal Liberals are also BC Liberals. So it is natural that the BC Liberals have the support of many of the federal Conservatives and only more far-right federal Conservatives back the small and disorganized BC Conservatives, which are very far on the right. The BC NDP is a center-left party and includes some center-left federal Liberals in addition to federal NDPers.
Saskatchewan is currently the only province with only two parties represented in its legislature. There are, of course, other parties in Saskatchewan, including some that could theoretically win seats. A number of other provinces are effectively two-party provinces as well, though all have a least one member of a third party currently in office.