Muggleborn Slytherins who at some point get in despite their bloodlines because their ambition and willingness to go far with it are just that strong.
Muggleborn Slytherins who hang out, and decide as a group to bring down the rest of the house who are jerkasses to them.
Muggleborn Slytherins snidely and subtlety using their housemates to achieve their own goals and work on the racism entrenched in the system.
Muggleborn Slytherins who use muggle terminology and references among each other to confuse and mess around with asshole housemates.
Muggleborn Slytherins who go out of their way to hang with the smart but flighty Ravenclaw weird kids, the Brave Gryffindor kids and the Hufflepuffs who’ll work to better everyone.
Muggleborn Slytherins who want to change the world, not rule it.