Pokémon Species modification is quite simple. All you must do is enter the pokémon digit (found in the accompanying file named 'Digits') into the circled box on the picture below. Now just hit save!

Too add new pokémon to your line up just enter the pokémon digits on the Pokémon Species box on the tab following your last pokémon, For instance. If you have 3 pokémon, then enter the pokémon digit into the Pokémon species box on the Pokémon 4 Tab, now save and its done. If you have 1 pokémon, enter the digit on the Pokémon 2 tab, and so fourth.