Hal (Bryan Cranston) was in just as many episodes of Malcolm In The Middle as Malcolm Was!
When a show has a title character, viewers expect to see them in every episode. Supporting characters appear in most episodes, but may not be there for an episode here or there. They may be "on vacation" or "sick."
However, this was not the case with Malcolm in the Middle. The show's title character, Malcolm (played by Frankie Muniz) appears in 151 episodes. However, the other characters who play his family, Hal, Reese and Dewey, also appear in all 151 episodes. Francis and Lois also appear in all these episodes.