Your humble correspondent hadn’t heard of a Green Party candidate and couldn’t find the candidate on the Elections Canada site. But, as so often, he was wrong.
There does seem to be a Green Party candidate—although Elections Canada will be surprised to hear it: John A Johnson. Johnson is even campaigning, and he has said he will participate in the debates likely to be held on September 28. Of course, Johnson is vanishingly unlikely to win, but his candidacy will challenge Mike Sullivan.
Sullivan is already facing a challenge. The NDP is now trailing the Liberals in York South—Weston, according to Threehundredeight.com, which says that Ahmed Hussen, the Liberal candidate, has a 62% chance of winning the riding. (The site does say that these are “riding projections” and “not polls”, and so they may not be accurate.)