Scarlet Badis are for species only tanks. They aren't good with any tankmates really besides shrimp due to their super small size and they aren't very quick at getting food. Any other tank mates would snatch it up. So IMO, I wouldn't do it. You could keep 2 in a 5 gallon tank.
Flame - Red and Blue Veiltail Male
Oswald - Blue Halfmoon Male