I'd watch out for Spinner pushers. These spinners take a particularly hostile approach towards enemy sumo drones, but its hits are rarely lethal until the arena closes in on the drones and gives a small enough area for the weak hits to effectively reflect an enemy out of the ring, but they also are far more effective against pushers, effectively negating the weakness passive, center-seeking spinners have by using the pusher's force to accelerate its own spin speed until the inevitable ring closing in and pushing the pusher out.
Not all hope is lost, however, as a new pusher sub-type has been built specifically to melt spinners through faster-than-rotation bursts of speed, crashing into the spinner and wiping out internals. These drones shall be amply named "Crashers". I need more research on Crashers before I can name any other strengths or any weaknesses, but the fact the spinner omnipresence has been challenged shall bring light to the sumo tourney world.