Not sure why the standard TG manaphy isn't seeing much usage. With the rise of bulky teams it's fairly clear that it has a good matchup vs common things like slowbro + tran, and its speed is nice in that it eliminates all of the things that speed creep + speed base 70s, along with + speed base 80s. On top of that, it has the versatility to run rain dance TG and rain dance cm, while being able to cover a huge amount of things with its coverage (eball/ice beam/psychic/hp fire if you're style).