I treated my betta with aquarium salt and ich medication. The medication turned all the silicone parts blue, so if you have something valuable I would remove it from the tank.
My tank was much smaller so I am not sure if it would be safe to treat in a 10 gallon, but you can also do a hospital tank.
Ich is a parasite so you will need to treat the entire tank regardless, disinfect everything and dry out all toys and decorations for a few days.
I kept guppy at 86F, but don't raise the temperature too fast, only 2 degrees a day as more might shock him.
I cannot say for the other fish as I only have experience with the betta. I am sure there are more experienced people on here who can provide more info, but I hope this helps.