Apart from the really rare cards, most Yu-Gi-Oh
Some giants, like Theross Titans, made a big splash in the game, but they're a bit of a mixed bag, with some pretty powerful ones to choose from when building a deck
While we have more than enough actual slivers to choose from, there are a few changeling cards that might be considered: Mutavault, Shields of Velis Vel, Amoeboid Changeling, Blades of Velis Vel, Shapesharer, Mirror Entity, Taurean Mauler, Chameleon Colossus
Eventually, the ban hammer struck it down, removing it from the Modern format
Without the opponents cooperation, you have to do the work yourself with Ingest creatures, which seems like a pretty low power-level and worth avoiding in Constructed