I chose the Irish Elk as a base animal because it can easily exude a grass-type vibe for being a forest-dweller. While quadruped starters got shafted in the recent generations's trends, it is more forgiving to have a Grass quadruped starter because of precedents like Venusaur, Meganium and Torterra.
For the design elements, I opted for prickly leaves like the
Holly on the fur to bring out a decent mesh of Grass and Electric typing, at least color scheme-wise. For Grass type visual cues, the neck is made to look like a tree trunk with the horns as exposed branches and the mane as the foliage. "Roots" dangle around the legs. Lightning hooves and horns made to loosely resemble a Railgun's nozzle are added to support the Electric typing more.
As a design quirk, I wanted to give a jobclass theme amongst my starters, much like what has been done on the Gen 6 and 7 ones. This design in particular follows a Druid-class aesthetic, which the Irish Elk naturally portrays. Although Druids throughout RPGs differ slightly in role, they are mostly casters that can transmogrify into beasts (mostly deer, bears or birds of prey), use healing spells, and use the forces of nature like earth, wind and lightning; a good fit for Grass/Electric for sure.