Bullying Guppies Help!!!

As a favour to someone who had bred too many I took 3 male guppies last week. Put them in my tank with 1 remaining male guppy, pair of dwarf gourami, 4 platies (1 male, 3 female), green neons, few cories, harlequins. They are like little Red Devils and have been bullying my male platy and have chewed lots of skin from under his gill area with some blood staining... I'm worried he is going to die... And really regret these 3 new additions.
My 2 other tanks one has a male betta, slender harlequins, cherry barbs  and neons... The other female Bettas, pair of rams, golden barbs, tetras ... Not sure who to shift where or to just humanely remove the new 3 ...
Thought of putting my male to recover in my under stocked tank with male betta  he isn't at all aggressive to other tank mates but still heard bad things about mixing then!!!
Please help!!!!

The other guppy is untouched... Did have loads of male guppies before but gradually over time they have died, the original one is placid as anything and the new ones aren't fussed about him.... One of the harlequins had a go at one of the newbies as the guppy was giving them grief... Just saw one of the guppies going  for a female platy but she saw them off...

Think I will contact local fish shop to see if they will have them but can't for a couple of days due to work....  Think my male platy may pass away before then 😢 could he be put in either tank before I can get rid of the terrible trio???