Complex sentence: Ryotaro rarely uses this form, as it has the weakest armor and pales in comparison to the abilities of the other forms, unless when he either does not want the assistance of the Tarōs or transitioning into Liner Form.
Split into simpler sentences: Ryotaro rarely uses this form, as it does not have sufficient armor and pales in comparison to the abilities of the other forms. Only when he does not want the assistance of the Tarōs or is transitioning into Liner Form.