Just checked and I can 100% confirm this now. Just retrained a greninja from scratch using rest bag and counted. Did 4 atk/ 252 sp atk/ 252 spd, then tried to add the last 2 to sp atk. That failed, so I tried speed which failed again. Then I tried atk and it put 2 in, so they were definitely spare and I hadn't miscounted. Either the cap has changed or super training maxes at 252 not 255. It's pretty awesome and I think people need to know this.
