If you were to choose an animal companion like a rhino or arsinoitherium, with the Powerful Charge ability, does the damage from that upgrade when your base damage increases, too?
For example, arsinoitherium goes from 1d8 gore to 2d8 gore + 2d8 powerful charge when it goes from medium to large at level 7. If you choose that for your animal companion upon entering Mammoth Rider, and your base damage goes from 2d8 to 4d6, does your powerful charge damage get an upgrade, too?