For an easy way to morph enemies, have W-Magic Materia, Gravity Materia + "All" Materia, and Morph Materia. Have someone else cast Reflect on the party, then have the person with W-Magic use Demi 3 on your party twice. It will reflect and hit the enemy six times without killing it, but will greatly reduce it's HP's. At this point, you can easily morph it.