So, I just checked, and actually most Grass-types in the Paldea Dex do learn Trailblazer. There's only 3 exceptions: Shroomish family, Rotom-Mow, and Foongus family.
Shroomish family is the most interesting here, not cause of Shroomish, but because this excludes Breloom. Apparently, and using the actual Move description, the following Pokemon are better at jumping at an opponent as if from tall grass than the boxing kangaroo/raptor mushroom: Sunkern/Sunflora, Smoliv/Arboliva, Petelil/normal Lilligant, Appletun, Bramblin/Brambleghast, Wo-Chien. And though SV doesn't mention it, this is from past Dex entries for Breloom:
BTW, Arboliva does have legs. I know, it was a surprise to me too, I thought it's body was just a brown tree base until I think I watched a playthrough and noticed it have white thing legs. And I used an Arboliva on my main team in Violet, though the feet aren't really noticeable from the back (also it was a special attacker and whenever it uses a special Move it just spins around in place).