Lol, if you think Pain Split is a form of recovery, then I'm at a loss for words. No matter how good a Pokemon is statistically, if it has flaws, it's going to be held down. Does anyone think, for example, that Kyurem was remotely feasible for anything but a Hail team? Venusaur has few resistances. It's not devoid of resistances like a Normal type or anything, but it's certainly not going to enjoy being worn down by STABs. Venusaur lacks access to Leftovers, and in a game where you would often switch in and be forced to switch right back out, passive recovery is invaluable for a wall. Finally, Synthesis is impeded by weather, which while not as omnipresent as Gen 5, is still very relevant. You could theoretically run Mega Venusaur with Sun and have a hybrid Chorophyll sweeper+tank or something, but that's an awful lot of work just to ensure a low PP recovery move can properly function.