Not on PO it isn't which makes it sound more like a issue that needs looking into immediately since +2 STAB Giga Drains to help with LO recoil is pretty insane if its illegal but I have to agree Growth with 3 attacks LO Venusaur is absolutely ridiculous and quite unpredictable being able to OHKO a huge ammount of checks outside of the weather inducers and Heatran.Illegal, you have to use Energy Ball as Giga Drain is a Gen IV TM and thus incompatible with Chlorophyll.
I honestly wouldn't bother with Sleep Powder to shut down counters because when you have something that bulky and strong your counters tend to be only a very select minority who you can build the rest of your team to take out, 3 attacks is what makes it. Effectively if the sun stays out which isn't exactly hard to do if you don't play it at the very start when you can clearly see they also pack a weather inducer all it takes is 1 turn to have a Venusaur with three of its stats completely doubled.
Although I think it really comes back to a similar issue as with what happened with the Rain debate that its these +2 speed abilities in combination with perma weather that is biting hardest.