Did Mayweather struggle with movers? The only fights he had where the scorecards were close that I can think of were Castillo 1, Maidana 1, Oscar, and the Cotto fight. None of those guys were movers.
Saldivar beat Winstone, Seki, Fammo, Laguna and Legra, all superb movers. As good as anyone I've seen in gradually getting to a moving target in increasing increments over the rounds. Fuller was a horrible fighter to deal with if you weren't a Tiger or Lausse with freakish strength or power and couldn't back him up, regardless of the ungainliness and average technical ability from the legs up. Very good footwork and a natural sense of offensive timing and momentum coupled with horrible mauling and usually plenty of help from the ref and judges. Naples was tremendous at using little, light half steps and subtle glides almost unconsciously to always prevent opponents from establishing a preferred distance or moving out of his range. Brilliant at it, and obviously with great upper body positioning and punch slipping ability to set up counter combinations. Shibata is another who I think was a swine to handle if you weren't a puncher or aggressor, again with light, quick feet, handspeed, excellent form in his hook and jab in particular, a refined combination puncher. And really hard in a manner like Saldivar and Ohba to knock out of his zone once settled and in a groove. Obviously though a weak chin, porous defence and generally less than the sum of his parts.
Hearns was basically immune to movers. His height, reach, speed and jab made it virtually impossible to slip around outboxing and evading him. On top of this he had one punch power and a debilitating hook to the body.