Power Rangers First Battles in Neo-Saban Era?

So I've seen a load of polls asking about favourite Red Rangers, Blue Rangers, Pink, Yellow, male and female Rangers; all that stuff, but funnily I don't see many regarding the sixth Rangers. That may be because I don't look too hard, but still.
For those unaware (and if you are, why are you on this page?), each Power Ranger series starts with a set number of Rangers, usually five, although on several occasions there have only been three to start off with. At some point later in the season, they will acquire at least one new member of the team. Usually this will be the sixth Ranger, although...