There's no difficulty setting in Pool of Radiance, they added that in Champions of Krynn.
Just use all humans if you want to transfer your characters. If you don't, don't worry about it; Pool of Radiance adjusts many of the fights to your party strength anyway.
If you're not familiar with the fantasy stereotypes, here's a party for Pool: human fighter, half-elf fighter/cleric/mage, elf fighter/mage, dwarf fighter/thief, human cleric, human mage.
For any other game except Secret of the Silver Blades and Pools of Darkness, go: human ranger, human paladin, elf fighter/mage, dwarf fighter/thief, human cleric, human mage
For Secret and Pools: human ranger, human paladin, human ranger (change to mage at 9th level) dwarf fighter/thief or elf fighter/mage/thief, human cleric, human mage
Oh, and due to the 1980s gender roles, don't make more than one of your fighters female, because they have lower maximum strength. This was fixed--in the second editiion, which these games predate.
Post edited August 31, 2015 by Null_Null