Wild Nacatl gets +1/+1 as long as you control a Mountain.
Wild Nacatl gets +1/+1 as long as you control a Plains.
10/1/2008 Wild Nacatl’s abilities check for lands with the subtypes Mountain and Plains. Those lands don’t need to be named Mountain and Plains. Wild Nacatl will get both bonuses if those two subtypes are contained among the lands you control, even if they’re from the same land (such as Plateau or Sacred Foundry).