If only for the time it takes your 30gal to be ready, you could keep one Angelfish juvenile in a small uncycled tank or adequate plastic recipient if place an airstone AND if you do have stable parameters in your source water (mine does not) by doing huge daily water changes as far as you manage to match temperature (incoming water temp = tank/recipient water temp).
I intervened with one Angelfish that was being bullied once a pair was formed out of six. That fish was among the four I relocated. I placed him/her for a week or so in a 5.5gal tank that was housing a male
betta, 2 Ghost Shrimps and a Nerite Snail. I kept my eyes on water parameters and performed water changes when Nitrates hit 25ppm; that tank's bacterial colonies handled the
bio-load, but it was a risky emergency move. I ended relocating him/her in another 5gal I was cycling for hospital use -once it cycled- since I was concerned with my Betta well-being.
Today that particular fish is paired-off with one of the Angelfish that was previously bullying him/her.
A tank divider, as Mike19 suggest would work well: leave at least two gallons of water for your bully one by placing it at 1/5 the length of your tank so your three
goldfish and the other Angelfish juvenile have some room.
Pepe
Santo Domingo
Pepe
Santo Domingo