Yes, but only if you teach it ancient power.
Swinub evolves into Piloswine at level 33. After that Piloswine can evolve into Mamoswine if it levels up while knowing the move AncientPower.
Mamoswine doesn't evolve either way because it doesn't exist in Pokemon LeafGreen. It evolves from Piloswine who evolves from Swinub, but Piloswine can't evolve into Mamoswine in LeafGreen.
Piloswine evolves into Mamoswine if leveled up knowing AncientPower
Piloswine does, it evolves into Mamoswine.
The Pokemon Piloswine evolves into Mamoswine when leveled using Ancient Power. It evolves from the Pokemon Swinub at level 33.
A Mamoswine evolves from a Piloswine which evolves from a Swinub.
You must learn it Ancient Power and then you level it up. Then it evolves into Mamoswine.
Piloswine evolves into mamoswine when levelled knowing ancient power
Piloswine is an Ice and ground type Pokemon that evolves from Swinub at level 33. If it learns Ancient Power, it will then evolve into a Mamoswine.
swinub evolves into piloswine at Level 33 and then it evolves into mamoswine when it gains a level after learning ancient power
Piloswine evolves into Mamoswine when it levels up when it knows ANCIENT POWER. ANCIENT POWER is an egg move, so you probably need to do some breeding in order to have a Mamoswine.
Piloswine evolves into Mamoswine when he learns AncientPower, sometime after Level 33.