Alternatively, you can teleport. That sort of screws up Spencer's approach game, especially if the teleport isn't relative to enemy position, such as Skrull's/Deadpool's. On the subject of Skrull, it's roughly a 70/30 in Skrull's favor since Skrull can grab Spencer out of the air with Heavy Elastic Slam. And since Spencer has no realistic approach outside of short-hop ziplining, it's very bad. He can have a projectile assist protecting him but then you've got an air dash that puts you above Spencer and an aerial command normal that causes ground bounce on hit. And if you're really screw, you can Meteor Smash away.
Haggar has the ground pipe, which causes ground bounce on airborne opponents. You can naturally cancel it into light Hoodlum Launcher before he hits the ground or even just the standing S launcher.
MODOK causes some problems for Spencer as well, although his large hurtbox sort of makes it difficult. You can spam Medium Analyze Cube to block off aerial approaches and be a troll in general and if you have any Levels of Understanding, enhanced Barrier completely screws up Spencer's approach outside of Bionic Lancing through it.