Pegasus: Uses two Thunder, three Light, two Water and one wood type. Use Earth, Thunder, Wind, and Fire types. Board: Light: 55, Dark: 25, Water: 15, Wind:35.
Ishizu: Uses five Light, three Wind types. Use Thunder and Wood types. Board: Light: 40, Wind: 30.
Marik: Uses four Fire, two Earth, and one Wind type, Use Water, Dark, and Wood types. Board: Light: 55, Water: 40. Note: You can and should use fire types, the board will become a Fire zone and give Marik's fire types a huge boost and other types will take field damage.
Shadi: Uses four Dark, two Thunder, and one Fire type. Use Light, Earth, and Water types. Board: Will start at Dark 60, but one of the Great Dragons breath will turn it to different elements.
Seto: Uses two Water, three Light, one Earth, one Wind, and two Fire types. Use whatever you like. Points are unlimited, but remember AP is not. Choose a few monsters that give you a nice amount of AP when you summon them. Board: Light: 80, Wind: 30, and also Water. However, when the clouds cover the sky the board becomes Dark: 80. This is the board to evolve certain monsters. When you complete the game, keep playing to get different monsters.