Subverted: Herman has the appearance of a sixth ranger because he helps the heroes on a particular mission, but he doesn't join the team.
Double Subverted: He joins later.
Parodied: The Five-Man Band named "Five Man Band" receive equipments or powers that require a sixth member. So they hire Senso Ranger, a temporary worker whose job is to help the team.
Herman starts out as a Sixth Ranger Traitor, but then moves to the side of good. He is then reminded of his debt which he must pay the Dark Side. He also becomes emotionally attached to Alice, she then finds out. He does not want to cause shame to his country, but now Alice is pregnant, creating a Soap Opera-style father plotline.
The additional party members don't join the party, because it's full. Instead, they give the party effects, e.g. Instant Healing, HP+10 etc. However, they all have triggers, and their skills must all be attached in the skill slots, but since they can only be on one party member, they'll take the trigger. For example, Herman's song is triggered when all party members reach Critical Condition to raise all their stats, and if you put Kitty's Magisplosion in one of Bob's Skill Slots, Magisplosion will consume all of Bob's Mana to KO an opponent as a Last Ditch Move when Bob's almost KO'd by magic. In other words, they're much closer to Mons.
Herman never joins the team and becomes a normal character as soon as his intro arc is done.
No new characters are introduced.
Enforced: "We need a new guy! Someone to shake things up, and more importantly, provide a boost in toy sales!"
Lampshaded: "Good thing we added you to the team. What would we ever do without you?"
Invoked: Bob puts an ad out in the paper for a new guy.
Defied: Herman refuses to join the team and becomes an NPC immediately after his introduction scene.
Discussed: "I think it's about time we brought in a new guy. What do you say?"
Conversed: "The bad guys are beating the good guys by hitting all their weak points and dodging their best attacks! Their only chance would be someone with a different set of skills and powers, like the completely unrelated guy they introduced five minutes ago... and here he is!"
The Team needs another hand so they find one. It takes some time for him to get used to everyone and they him, but it eventually works out or it doesn't he leaves.
Herman's motives for joining are kept to himself and his powers/knowledge makes the others suspicious.