I played Pirates in On The Edge and did well, lost to Dinosaurs but then won the next three.
It's not OTE-legal, but here's my Slimes deck:
Deck
4 Forest (MKM) 286
6 Island (MKM) 279
2 Boseiju, Who Endures (NEO) 266
1 Otawara, Soaring City (NEO) 271
1 Hedge Maze (MKM) 262
4 Restless Vinestalk (WOE) 261
2 Field of Ruin (THB) 242
4 Consider (MID) 44
4 Otherworldly Gaze (MID) 67
4 Founding the Third Path (DMU) 50
4 Picklock Prankster (WOE) 64
24 Slime Against Humanity (MKM) 177
You're right that the lack of removal hurts. Sometimes just having huge creatures isn't enough.