Fawkes was the most notorious plotter chiefly because he was the one caught trying to blow up the gunpowder, but the actual head of the plot was Robert Catesby. So a Gunpowder Plot without Fawkes would be much the same as IOTL, but with someone else tasked with lighting the match.
Of course, what would be fun is if our Puritan Guy Fawkes also decides to blow up Parliament at the State Opening. I wonder if the two groups of plotters would discover each other, and if so, what they would do? I can't imagine either being in sympathy with the other group's aims, for all that they both hated James. Maybe one group would dob the other in to try and get in the King's good books and convince him to show more tolerance ("See, your Majesty, we just saved your life from those evil Papists/Puritans, clearly we aren't disloyal or subversive so there's no need to persecute us") or to draw away suspicion from their own plot ("Those scores of gunpowder barrels I'm storing under Parliament? Make no notice of them, your Majesty; after all, if I wanted you blown up, I wouldn't have uncovered that plot to you, would I?").