What’s the difference between the difference AI characters?

Each character has a slightly different set of rules used to decide how much to bid, when to pass, what cards to pass or discard, and different strategies for choosing trick cards to play. Each character is rated on a scale of 1 star being the lowest to 5 stars being the highest. The 4 or 5 star characters are stronger players and will be better partners or more difficult opponents. The 1 or 2 star characters are weaker players and will make for a poorer partner or easier opponents. The 3 star characters are somewhere in the middle.