Elastics can be placed in many different ways, on braces or with aligners, and can move teeth in different directions. There are inter-arch elastics – ones that connect the upper and lower teeth and are active (they stretch) when you open your mouth – and there are also elastics that work within a single dental arch. They can pull the teeth front to back, vertically and sideways. There are alternative appliances that can be used instead of elastics – a Class II corrector, mini-screws, a Herbst appliance, headgear and others.
This answer is for general information. Your own case needs an examination by an orthodontist.