A creature that gets +2/+2 from Kodama's Might will still get +2/+2 despite Sudden Spoiling (whether Sudden Spoiling resolves before or after Kodama's Might). Note that Sudden Spoiling uses the form "base power and toughness", not just "power and toughness" (C.R. 108.1); the text "base power and toughness" clarifies that certain other effects can change a creature's power and/or toughness (layers 7c-e under C.R. 613.3c-e; "base power and toughness" applies in layer 7b under C.R. 613.3b). See also this thread and this thread.
Sudden Spoiling - Basic question.