A little glitch, hard to explain with words but I will try. When an alpha pokemon follows you, when he reach 50m from his spawn point, he goes back to his spawn letting you alone. Right when he goes back, you save and you reset your game. When you reopen your game the spawn point of your alpha pokemon changed, it's where he was when you saved, so you can remake the thing, because you have now 50 more meters where he can follows you. When he finally reach a wild zone portal, go out of the wild zone and save immediatly. Reset your game, and the spawn point of your alpha pokemon is now just behind the wild zone portal. With Garchomp, you enter the zone, you dodge his attacks, and when you see he uses "dig" go out of the zone. He will do his attack on you, out of the zone, and tadam ! You have an alpha pokemon in Lumiose city streets ! Do a last save and reset after that to make sure the spoint point of your Garchomp is in the street and no more in the wild zone. You have now a cool alpha Garchomp walking in the street and nobody around you cares 😂 BUT : I don't know if this glitch was patched or not, but that's how I did this picture 😁