Well the betta might attack the shrimp and the snail, but some won’t. Same goes for the lampchop rasboras, some people had problems with them. It’ll be better to stick to harlequin rasboras IMO. The success rate is higher. It just depends on how aggressive the betta is, how many hiding places there are and the tank size. Cherry
barbs and a betta needs at least 20g.
For example, my betta can’t stand anything that’s alive.However, I had a betta before that only attacked its tank mates when I first added them. I have even heard of male bettas not are not aggressive to other male bettas.
So it really depends on the betta itself