Seven star raids are special, they form where an excessive amount of energy is formed, much more then the normal 3/4 star. Since six stars naturally only spawn once a region (3 a Day) how would a seven star occur in nature
hmm, fair enough, though how would you explain it being in the terrarium and it being able to breed (unlike mewtwo) [also just treat this as a friendly argument, I'm not trying to be rude or anything]
All confirmed artificial pokemon are clones, the reason they are incapable of breeding is because they were legendary pokemon, the ancient pokemon that were revived were able to breed before
Charizard is an artificial pokemon, it's only obtained by professor or people who study pokemon for research and never in the wild. It also has two mega evolutions and the only other pokemon with that is artificial. Based on its appearance we can assume that for the body might've been trying to clone an Aerodactyl and do to the flames outside its body the other sample used in its creation was a ponyta/rapidash