This trophy is made easier by making sure you transform your character.
The power ups come from the light blue enemies that jump towards you, you need 3 power ups to complete the transformation.
If you miss one of these power ups, you should probably start over because there are just enough to complete the transformation in the first level.
Once you transform into the altered beast, continue the level and defeat the boss. You should get 100,000 points from defeating the boss and pop the trophy.