1) Including the "Onyx holding a hard stone executing Earthquake in a Sandstorm against a Flygon with the ability Hover?" state is just doing an N-constraint solver. Since multiple dispatch is a generalized system, we can dispatch on N different types.
Take the "Dual Type" in Pokémon for example: https://pokemondb.net/type/dual. You'll notice that instead of just an NxN grid, we're dealing with an NxNxN. Where a single attack needs to be related against 2 different defenses.
Simple enough `eff(atk::T1, def1::T2, def2::T3) = ...`, the we can just encapsulate this second type within a `Pokémon` structure and route to the correct function dynamically.
2) The "Super Effectiveness" of a MD system is that you don't _need_ to put everything into a singular table, something that's functionally impossible to extend. The idea is that we can build up the correct relationships between types completely independent of one another. The issue is, who owns that table? How do you merge more than one new type in? (see my section about Composition in the post)
If someone else wants to make a new `Foo` type Pokémon, and another person is doing `Baz`, they can work completely separately, only defining the `eff` functions _only_ concerning their type. And there's _zero_ integration work to use both, just import the new types and their functions. This is incredibly extensible!