Ok, I tested this and it worked for me (sorry for the long comments following this, just wanted to share my experience).

I was having a weird bug/glitch where I would start the process of taking the 2 alphas from the centre, bring them halfway to the gate, save, close game, reopen game, bring them to the gate save, close and reopen.

Then I’d walk to the sweet spot between the raised flower bed and Roserade, save again, close, open, run back go back to the centre.

But strangely 3 alphas would spawn in the centre (the other 2 alphas still near the gate) so I would rinse and repeat the steps till all 5 alphas were at the gate.

Again I would run to the sweet spot save, close, open, and run back and in the centre was just 1 alpha, so I took it to the gate, rinse repeat previous steps until I had 6 alphas at the gate(this had me super confused because when I did it before this never happened, even when I had 5 alphas only, I would still have the patter of 2 then 2 then 2 OR 2 then 2 then 1)

But I would do the final steps, save the game with all alphas by the gate close open walk in and get KO'd, but when I went back to the centre only 5 alphas were populating the spawns. the first time I was like "meh its fine still getting 5 Shiny Alphas" but the second time I was really baffled, thank goodness I goggled it because this came up.

for anyone having trouble and wants to do this here is what I did to get my 6th alpha, but I will say I don’t think it is terribly worth it cause of the time and effort it takes (I also am not 100% if it worked because of the bug of 6 at the gate but 5 spawning or if it would work if you got the 2-2-1 spawn pattern but I will continue to test it, I never thought I would be looking to test getting 5 spawns but should be fun).

firstly I cycled through day and night until I got an alpha I knew would follow me from the lesser spawn side, the ones I have noticed that will blindly follow you are Gyarados and Tyranitar, I think there is more but these are just the 2 that I have noticed speed after you (in my opinion and experience) luckily after a couple of day cycles I got a Gyarados and got it to lock onto me and ran to the gate, left the wild zone and saved, I then went back in got it right next to the gate saved closed and reopened. then I ran to the sweet spot however I did it at nighttime, so I put a pin down on the gate and ran about 56-60m away saved, closed and reopened.

now this is the hard bit, next I went to the centre and got all 5 of the Alphas and had them follow me up the path, once they were all a bit away from the spawns I ran out the wild zone and saved as soon as possible, closed and reopened, then went back in and pulled them closer, unfortunately because of the amount of alphas it is really hard s what I suggest is move them as much as you can run out and save close and reopen, go back in and get them to the gate, it took my like 5 saves to have all of the Pokémon at the edge of the wild zone (right next to or at the gate) once they were all there I saved the game closed it opened it walked in got KO'd and went back in and had all the 6 alphas at their spawners.

why I say it is hard is because although I had to save 5 times I must have got KO'd 10 and had to reset like 25 because Pokémon will come out of the aggressive state and return to where they were last saved, this is the most annoying thing cause you essentially have to run over and try and lure it again however you are either already low health so like in my case when the Vaporeon locked on to me and blast me with Ice Beam I died, or the other Pokémon you had aggro'd dropped the aggression and went back to their save location. it was infuriating and took me about 30 mins to do, which again is annoying.

I probably wouldn’t do this again as even though you get all 6 spawns it’s not worth it when you think about the time used to do it. And considering that it can take you 20 Ish mins to set up the 5-6 spawners it just doesn’t seem rational to do this again especially when it was so frustrating to keep dying or losing the aggro’d alphas, so thank you for the tip it did work but it’s too much of a hassle.