Phil Reed over at Battlegrip speculates on the specific rights Diamond Select Toys has to Battle Beasts. I actually discussed this on PGPoA way back in 2009, and even then it was rumored DST only had the trademark on the brand name, not the creature designs (or the rub-sign feature).
It seems obvious TakaraTomy (the Japanese rights holder of Transformers) still has the rights to Beastformers, the Japanese toy line that became Battle Beasts when imported to the U.S. and Europe. As the original name suggests, in Japan the line was tied in to Transformers (specifically the Japanese Headmasters franchise). And now it looks like TakaraTomy may be moving forward with some new product under the name Beast Saga.
(A brief aside to Phil’s main question: I suspect the confusion over whether DST “paid someone” for the trademark is due either to someone at the C2E2 DST panel misspeaking, or someone misunderstanding or misreporting what was said. I do think they simply snapped up the trademark when TakaraTomy let it lapse. Also, I believe you pay the government a fee when you pick up a lapsed trademark, so that may be what the “paid” is referring to.)