Toxtricity as a whole also has very similar vibes to Lucario, who is basically Gen 4's designated shillmon, and Toxtricity was definitely designed as a mon who was meant to be marketable and one of Gen 8's "shillmons" who is popular and sells. Toxel is a "baby Pokemon", one is given to you as a gift in game, Toxtricity has two distinct forms and a striking design, and it has a G-Max form that was treated as special amongst most G-Maxes.
In general it seems baby Pokemon who are officially classified as such are pre evos of mons who they want to be popular/marketable and sell from a popularity and merchandise standpoint, and/or are added pre evolutions post Gen 2 to a mon who was previously an unevolved Pokemon as a coding loophole to work around "retconning" that completely.
Gen 2 had a lot of them because that was Gen 2's "gimmick" so to speak, and what gave Gen 2 its identity. Even then it mostly targeted popular Pokemon such as Pikachu, Clefairy, and Jigglypuff. The one totally new baby Pokemon was Togepi, who was sort of a poster child for Gen 2 given it was marketed heavily and was owned by Misty in the anime for a long time. Riolu and Toxel fit the bill of marketable as well, considering Lucario and Toxtricity have that "mon who is designed to be popular and merchandise worthy" vibe.
The other cases are cross generational pre evolutions. Wynaut, Budew, Bonsly, Mime Jr., and Munchlax were all introduced after their evolutions and tied to incenses so that breeding wise they still had a loophole addressing them.
In general these seem to be the two trends with some overlap between them.