Common to both acute and chronic malnutrition is –
Weight for height is decreased in both acute as well as chronic malnutrition. However, it cannot distinguish between acute and chronic malnutrition.
Therefore, weight for age is a common indicator to reflect both acute and chronic malnutrition. However, it is not the best indicator for this (as weight for age cannot differentiate acute from chronic malnutrition).
Best indicator for this purpose( to differentiate acute from chronic malnutrition) is the simultaneous measurement of 'weight for height (wasting)' and 'height for age' (stunting)'which is useful to understand the dynamics of malnutrition, distinguishing between current ( acute) malnutrition and long term (chronic)malnutrition.
So, for both acute and chronic malnutrition: -

i) Single common indicator → weight for age
ii) Best indicator is simultaneous measurement for stunting (deficit in height for age) and wasting (deficit in weight for height)
Weight for age
Weight for height
Height for age
BMI