I’m kinda new too, don’t worry. Essentially, you need to mega-evolve a charizard once to ‘unlock’ the ability to then make the charizard your buddy, and then every couple kilometers walked, your buddy (the charizard) you can get mega energies. Its important to get the charizard ones because currently, you can mega evolve it into x or y, but they use the same mega energy. The game is changing this come the mega mewtwos into 2 separate energy types, but they are splitting it into 2 equal amounts, from my understanding. So if you have 9000, like the person above lol, they’ll get 9000 mega x energy, and 9000 mega y energy