BEAR said:
Link and Strangepork were only in Pigs in Space sketch if i am correct. Link was in the Muppet Movie though.
No, they were both used outside of Pigs In Space on a regular basis, although Link appeared outside PIS more than Dr. Strangepork did. Link Hogthrob regularly appeared in another recurring segment, bear On patrol, and he also appeared in many music numbers, including Sonny Boy, The Rhyming Song, and Macho Macho Man. There was also a solo number with him in the epsiode with Judy Collins, and he portrayed a mountee in Cloris Leachmans first number. He also studied how to be a superhero in the lynda carter episode. He also played one of the muskateers in the three muskateers segment of The Muppets Go To The Movies, and from what I understand, he regularly appeared in the controll room on The Jim Henson Hour, something that was rare for any classic character who wasn't Kermit or Gonzo (and also unusual because it was a Jim Henson character appearing backstage).
Some of Dr. Strangeporks appearances outside of Pigs In Space include the Wonderpig sketch from the Lynda Carter episode (which also featured Link), as a film director in the Liza Minnelli episode, in the closing number of the Peter Sellers episode, in the horror movie sketch from The Muppets Go To The Movies, and an appearance in Bay Of Pigswatch in an episode of Muppets Tonight!