Lucario isn't changed at all by 2-stock, or at least not more than any other character.
ZSS would be buffed for the time being, as she's MUCH improved by the suitpieces (IDK how much other characters gain from them), but over time people will get better at camping out the pieces. (Then again, didn't we say that about Diddy?)
PT is the most obviously buffed. Goodbye Ivysaur!
Wario is debatable. Less time for waft, sure, but also fewer wafts needed.
Beyond that, I don't think anything changes beyond psychological factors (for example, ICs need to get fewer grabs, but you don't need to "not get grabbed" for as long--under tournament pressure which does your brain prefer?) and obviously the different stock-to-time ratio.