After much consideration, I have come up with a more reasoned version based on science and shit.
Space
Attacking
2x: Steel, Flying, Ground, Heart
.5x: Rock, Grass, Bug
0x: Ice (could become resist instead)
Gravity will crush steel types in on their own weight. Sure iron can make your spacecraft fly, but in hyper-grav/extreme magnetism you're not going to want to be wearing plate armor. Likewise, gravity neuters the flying type, so a bird flying free will plummet and likely break. Meanwhile, on the flipside, the ground does not hold well under massive pressure and heart needs more oxygen. Fire meanwhile under great gravity can burn in other ways. Unless we add a magma type to represent burning magma, there's no way a lava slug should be weak to space as lava doesn't need oxygen, just massive heat from gravity.
Rock resist is due to the rocky nature of asteroids. Sure metals are in asteroids too, but not as prevalent as rocks. Bugs tend to thrive as light as they are and even can breath in space, likewise when space doesn't exist, so too doesn't temperature. Thus a universe without space (and by penalty time, but time can melt ice or something) is technically at absolute 0 Kelvin. Thus ice keeps space away. Grass is the one true filler here.
Defending
2x: Water, Electric, Dragon, Fairy
.5x: Steel, Normal, Ground, Poison, Flying, Fire
Water is heavy: unlike most things in the universe, its solid form (Ice), it's actually less dense than its liquid state. Earth is pretty dense and has a lot of water, although an Iron Core doesn't hurt. Meanwhile, Electric light zips through the universe at the same speed regardless of space or not. Fairies and their affinity with space can obliterate them, and Dragons? Well, dragons in this universe seem almost unworldly. Almost beyond time and space, so they say screw the rules and destroy both.
Steel again will either become too light or weighted down before they land, same with tackles being floated away and the earthly type is too grounded. Flying again could be splatted against the earth. The fire may not suffocate from space types, but the actual fire moves seem to mostly be fiery and not heat based, however, because there are a few like Heat Wave and Lava Plume not being combustion based, full on immunity wouldn't be a good idea. Poisons tend not to be as strong in a vacuum. The body doesn't function right, neither do the virus cells when they get zapped with radiation, a very space age technology thing. It's filler enough that it could be nixed.