Today, pumpkin is added to all sorts of beer styles. Traditionalists will add pumpkin to a pale-colored, lightly-hopped ale comprised primarily of American-grown 6-row malt. Honey and maple syrup may also be used, as they were popular fermentable substitutes used to inaccessible grains during colonial times.
Darker, roastier styles like stouts, porters and browns lend themselves well to the spices that accompany pumpkins in pie or other dessert dishes. The higher Lovibond specialty malts that create the robust flavors and dark hue make for a heftier malt backbone that can stand up to more aggressive spice additions.
And there are even Belgian styles, in which the esters from the yeast meld with the pumpkin to make a unique, yet delicious experience (see the “Saison D’Potiron” homebrew recipe featured in the September/October 2013 Zymurgy article “The Quest for the Perfect Pumpkin Beer”). Yeast that create clove and ginger qualities can be artfully used to mimic cooking spice additions that compliment the pumpkin.
Whatever style you brew, the goal should be balance–showcase the pumpkin and spices without overpowering the base style, but ensure the flavors aren’t lost.