Connections
Both are energetic children (Cuphead might be a teen) from 2017 indie games that use a specific style (rubber hose cartoons and 3D platformers).
Both made deals with entities (The Devil and The Snatcher) with their souls involved and had to do a number of jobs to get their souls back, including fighting the dealer.
Both are minorly selfish and greedy.
Battle Name: A Cup In Time