>>28671077My own personal headcanon is that Earth Ponies have magical potential at least equal to or greater than the average Unicorn. To the point of bending the very fabric of reality.
The problem is that they have no means to focus it, and use it subconsciously instead of consciously. This explains high-energy "party" type EPs usually strange abilities to create or procure anything they require at the moment from almost nothing should they really desire it. But at the same time, they themselves would have little to no means to replicate what they did, so if you strapped them to a table and asked them to give you another cake just like the one they pulled behind their back for your birthday party yesterday, they will not know how to do it.
This goes somewhat the same for "traditional" type EPs, except they have more power with anything geological. Unicorns have to study for weeks to months each to just make a single plant grow out of a pot, or practice levitation skills enough to lift a fairly large boulder, while a T-EP can liven up a farm just with their very presence and can lift or break the boulder with ease if needed.
Which has scarier implications with T-EPs such as the Pie family, who are bred to specifically manipulate the earth itself. With enough need, these kinds of ponies can create literal earthquakes and move mountains without any effort. Only problem is that they are either too shy, angry, autistic, or distracted for it to be any more than a very rare occurrence.
Which in conclusion, reveals Pinkie Pie being in possession of both "Party" and "Traditional" archetypes, putting her at a terrifyingly high level of magical potential, perhaps close to Twilight.
There are other archetypes for EPs, such as "Intelligence" where they trade strength for superior minds and have a very fine touch of the hoof to have an edge in crafting and invention, but I don't have enough space to talk about them all.