Use Pokemon to teach OOP for millennials rather than dull examples like "Car" or "Animal". They don't even drive car with combustion engine.

Pokemon.js

// --------------------------
// Base
class PokeDex {
    constructor(name, hp, atk, gen, type){
        this.name = name;
        this.hp = hp;
        this.atk = atk;
        this.gen = gen;
        this.type = type;
        this.rare = false;
    }
    printInfo(){
        console.log('hello ' + this.name, this.hp, this.atk, this.gen + ' generation', this.type, ' rare?' + this.rare);
    }
}

// -----------------------------
// Child 1
class EvolvedPokemon extends PokeDex {   
    constructor(name, hp, atk, gen, type){
        super(name, hp, atk, gen, type);
        this.evolvedDate = new Date();
    }
    happyBirthday(){
        console.log('My birthday of evolution is ', this.evolvedDate);
    }
}

// -----------------------------
// Child 2
class LegendaryPokemon extends PokeDex {
    constructor(name, hp, atk, gen, type, capturedLocation){
        super(name, hp, atk, gen, type);
        this.rare = true;
        this.capturedDate = new Date();
        this.capturedLocation = capturedLocation;
    }    
}

////----------------------------
// Misc Class - hold various information about the location
class Location {
    constructor(lat, lng, city, state, country){
        this.lat = lat;
        this.lng = lng;
        this.city = city;
        this.state = state;
        this.country = country;
    }
    printInfo(){
        console.log('('+this.lat+','+this.lng+') - ' + this.city + ',' + this.state + ' ' + this.country);
    }
}

// Test -----------------------------------------
var pikachu = new PokeDex('Pikachu', 80, 20, 1, 'Electric');
pikachu.printInfo();
var squirtle = new PokeDex('Squirtle', 100, 15, 1, 'Water');
squirtle.printInfo();
var raichu = new EvolvedPokemon('Raichu', 120, 98, 1, 'Electric');
raichu.printInfo();
var newYorkGreenvale = new Location(40,-73,'Greenvale','NY','USA');
newYorkGreenvale.printInfo();
var articuno  = new LegendaryPokemon('Articuno', 110, 90, 2, 'Ice', newYorkGreenvale);
articuno.printInfo();
var entei  = new LegendaryPokemon('Entei', 120, 100, 2, 'Fire', newYorkGreenvale);
entei.printInfo();

RESULTS.md

In your console, you will see something like this

hello Pikachu 80 20 1 generation Electric  rare?false
hello Squirtle 100 15 1 generation Water  rare?false
hello Raichu 120 98 1 generation Electric  rare?false
(40,-73) - Greenvale,NY USA
hello Articuno 110 90 2 generation Ice  rare?true
hello Entei 120 100 2 generation Fire  rare?true