Congrats on the shiny. And while Rock Tomb's power and accuracy buffs are both great and help Breloom deal with two weaknesses, I think the loss of a Technican boosted STAB that had perfect accuracy was still a major blow to it. But at least it still has Mach Punch, so it's not a total rain on the mushroom velociraptor's parade.
Ya MegaMom was by far the best power up punch abuser, still comes in handy quite a bit. Even if you just PuP on a switch and uturn out, the damage adds up. One of my favorite move additions of this gen.