2 squads with all range and 1 with all armor is good with xp hunting, since u can easily adjust the number of armor and range u bring into the xp hunt.
however this means u'll need to move at least 2 squads every time to make sure there are armor going with ur range
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but to answer about damage, unless u're going for an equal battle (which is pretty bad and should be avoid at all cost), don't use damage in ur army.