I don't think cleaner shrimps or cleaner wrasses can do anything to ich. They mainly pick up dead skin or left over food in the mouth of a fish.
Garlic may or may not help.
Sometime people reported that they added this and that and the ich went away. Well, ich just doesn't simply go away. Most likely they are still attaching to some fish but just don't cause an outbreak yet.
If you don't want to set up a hospital tank, then avoiding any stress on the fish is the best option. Feed it well, no aggressive fish. Stable parameters. Hopefully the fish can fight off the outbreak.
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