You will need to let it learn Ancient Power. You must have Piloswine remember Ancient Power by the Move Reminder and level it up at least once to evolve it into Mamoswine.
level it up while it knows ancient power
it evolves if you trade it with asoft sand
Teach Poliswine Ancient Power and it will evolve
ancient power is learned in the 30's lv
To evolve Pilowswine into Mamoswine your Pilowswine will need to learn the move Ancientpower. Then, it will evolve.
To get a Mammoswine in Pokemon Diamond/Pearl, you must teach your Pilowswine Ancient Power. Pilowswine can't learn Ancient Power, so you have to mate it with a male Pokemon that has the move Ancient Power. Wait awile then receive the egg from the old man and the baby Swinub has the move Ancient Power like the father.
Piloswine doesn't evolve by level; instead, it evolves when it levels up knowing Ancientpower.
Go to a Move Master and get him to teach it ancient power. Then level it up one level. Signed, N1TR01D
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Swinub evolves into pilowswine at lv 33 and to get a mamoswine you have to teach it ancient power ( if it doesn't already know this go to the move tutor) then level it up.
You must use a Heart Scale at the Move Relearner's house for it to learn Anceint Power, its a starting level move.
you have to trade a swinub.