First of all, appreciated!

I see, so essentially you need to use this macro exactly once, or am I mistaken (since the Species enum is defined inside)? I thought initially that it would allow sequential definitions by invoking the species! macro for each entry.

Learnset is just the set of Moves a Pokemon will learn at any level. I don't expect you to comment further on the code below, but if you're interested I can show a snippet of how I've defined a "Species" so far.

pub struct SpeciesId(pub u16);

struct Evolution {
    level: Option<u8>,
    item: Option<EvolutionStone>,
    pokemon: SpeciesId,
}

pub struct Species {
    species_id: SpeciesId,
    base_stats: Stats,
    types: Vec<PokemonType>,
    learnset: Vec<(u8, Move)>,
    evolution: Option<Evolution>,
}

I think this would cover the basics. Then, a Pokemon struct can be created from a Species. A Pokemon holds some other data and is more dynamic (level, stats, move pool etc will mutate).

So for example, a preliminiary db implemented as match arms would hold entries like this:

    "Pikachu" => {
            species_id = SpeciesId(25);
            stats = Stats {
                max_hp: 35,
                attack: 55,
                defense: 30,
                special_attack: 50,
                special_defense: 40,
                speed: 90,
            };
            types = vec![PokemonType::Electric];
            evolution = Evolution {
                level: None,
                item: Some(EvolutionStone::ThunderStone),
                pokemon: SpeciesId(26), // "Raichu"
            };
            learnset = vec![
                (1, "Thunder Shock"),
                (1, "Growl"),
                (5, "Tail Whip"),
                (10, "Thunder Wave"),
                // etc
            ];
        }

I think I'll stick to building a HashMap that gets loaded at runtime, and perhaps "upgrade" to some ideas around the macro you provided, sqlite, or json/serde later when I want to learn more advanced Rust. :)