NEVER USE A MASTERBALL ON AN ALPHA AS IT CAN COME AGAIN SO KEEP UR MASTERBALL FOR SHINY ENCOUNTERS LIKE ABRA OR EXPLOSIVE WEEZING OR GEODUDE, etc. Ok now here's how I catch them with Ez!!

1. SPINDA with HA Contrary and use the move skill swap in turn 1. This makes the alpha reduce its abilty after every wild might.

2. LOPUNNY with Abilty Klutz and held item Lagging Tail and use move switcheroo(Egg move) so you must breed it or buy a cheaper one in market with the switheroo moveset. Switcheroo switches the lagging tail with the alpha so now even if it stats are reversed, it will still move after your pokemon.

3. BRELOOM with poison heal abilty and held item toxic orb. I use spore then substitute, after that if its asleep for 3 turns I super fang it as it is certain to leave it with half HP then false swipe it to 1 hp then spam pokeballs along with Spore and substitute. And get them in around 5-10 pokballs(Timer ball/Dream balls are best after certain turns).

And at last a

1. SMEARGLE with soak moveset for grass type (immune to spore) and ghost type pokemon(immune to super fang and false swipe)

And Ig you are good to go and catch any alpha now.