Low Kick could be... interesting. It's not as good as it was back in RGBYFRLG, though, since rodents and puppies tend to lean pretty light. Still, you're looking at 80 base power on Lillipup after STAB, and 120 on Patrat.
We're nothing more than concreteness victims trapped into our limits
Blind beliefs that lead us: "Trust in what we can perceive with senses".
Thousands minds that reflect our tendency to flatten layers of knowledge,
demonstrating that we're just wasting our time.
Look above us, sky is just a fragment and shows us how we're nothing more than ants.
Human weakness is what we hide, overwhelming celebration of our fault .
Entwined with our fears of being in your hands, we're deaf to the universe that guides us.
How can we enhance our thin perception of every small wonder hiding behind simple shapes?
They're not going to remove 5th gen Pokemon from the Unova Dex.
They were actually catchable in BW1, you caught them in Challenger's Cave.
Here we go again. Any Pokemon that's in the Pokedex is a native to that region. The only reason Riolu isn't catchable in DPPt is because it was a design decision, they decided that Riolu is too rare to allow it to be catchable. It's likely that Riley and Cynthia got their in some area of Sinnoh that for whatever reason we can't access, much like how we couldn't access SW Unova, Reversal Mountain, and Humilau City in BW1.
Well sure, there's dozens of "what if" scenarios if you want to add Machop to the Unova Dex, but the Unova Dex is fine the way it is. Again, it's not about who or what, but where and when.
To be fair, you could ask the same question about Rattata, Zubat, Magnemite, and Grimer as well (and probably several more I'm forgetting).