UPDATED 10/13/11
Someone on Rangerboard, I forget who--I'm sorry, mentioned how there were patterns within a decade of Super Sentai, for example in the 90's almost every team had a Pink Ranger (only Jetman and Kakuranger didn't) and in 00's, there was very little Pink Rangers. I am only talking about how many members, the color choices and genders. So here are so patterns I notice....

1980-1989
Goranger, JAKQ and Battle Fever J paved the way but since they didn't have the same colors and had different formulas, I say it was a learning period. I think the 80's really established the formula of colors and also played with it a bit, patterns that would be used later and some that wouldn't as of yet. 6 out of the 10 teams had Black rangers and 4 had green. It was an unspoken rule that not one team could have both Green and Black at the same time, and it was sort of broken with Liveman. Go-Onger also followed this pattern for the main 5 (Zyuranger had 6 members). Speaking of Liveman, Liveman is the first to break the rule that girls could only be pink, yellow or white, a female blue---that would be done three more times later. Sun Vulcan is the first and so far only one to have three males and only three members. Bioman was the first to have two females, starting the yellow-pink trend
(first female yellow in Bioman as all other yellows at that point were male), which happened three times in the 80's. A lone Pink happened in 4 teams and
Pink Rangers were 8 out of 10. The pattern that has yet to happen was Changeman: ♂
Red, Black, Blue and ♀
Pink and
White. As of August, Gokaiger have yet to turn into any Changeman. Three teams were
Red-Pink-Yellow-Blue-Green and 4 were
Red-Pink-Yellow-Blue-Black.
This decade had 6 male Yellow Rangers and 3 female Yellows.




1990-1999
The 90's were more solid and rigid, the half of the decade the teams were
Red-Pink-Yellow-Blue-Green that was 5 of 10. There was 5 Black Rangers, 5
Green Rangers (not counting Dragon), 8 teams had
Pink Rangers like in the 80's and 2 female White Rangers instead of Pink. There was two light shade of blue:
Blue Swallow and Ninja Blue. There was five teams that had two girls and five that had solo girls. Zyuranger had black and green, but it was out of 6 but not out of 5.
Like the last decade, there was only 1 female Blue Ranger. Like the last decade, there was 6 male Yellows. This decade had 4 female Yelllows.
2000-2009
The 00's was very different, had some stuff more like the 80's and very contrasting than the 90's. There was noticeably less Pink Rangers than in past decades. Half of the teams had
Pink (5 Pink Rangers), 5 had Green (not counting Shurikenger), 4 Black Rangers (2 less than the 80's), and
three White Rangers in the main teams. Four teams started with three Rangers of
Red-Blue-Yellow (Hurricanger, Abaranger, Gekiranger & Go-onger).
Red-Pink-Yellow-Blue-Green pattern was used four times. Green and Black were used in Go-Onger like in Liveman. Gekiranger broke the mold with
Violet really late into the season, much later than a Sixth Ranger would show up and
White late into the game. This decade had two female blue rangers. 6 teams had solo girls (even though in Go-Onger, it eventually became 2), and 4 teams had 2 females. Also, this decade broke the rule on how many warriors you could have in a series. Dekaranger had 8 (and 2 guests), Magiranger had 8, Gekiranger had 7 and Go-Onger had 7 (first team to have two 'Sixth' Rangers).
Unlike past decades, there was only 4 male Yellow Rangers--in past decades, there was 6 each. This decade had the most female Yellow Rangers, at 6, hence flipping the scale.
2010-2012
Who knows what the future will entail, you can't really judge a decade by the first two because look at Fiveman and Jetman for the 90's; and Timeranger and Gaoranger for the 00's. Timeranger and Gaoranger seem pretty routine with
Red-Pink-Yellow-Blue-Green and
Red-White-Yellow-Blue-Black. Who could had known there was four teams starting with 3? And with the 90's, there was no other female Blue Ranger that decade. Fiveman used the
Red-Pink-Yellow-Blue-Black pattern, which was used two more times. So Goseiger had
Red-Pink-Yellow-Blue-Black and Gokaiger has
Red-Pink-Yellow-Blue-Green. I really find this interesting as many non-fans think the pattern is always the same. When there is no Black Ranger or Pink Ranger, I always get a question of where they are.



With Silver Ranger Pattern
There is also a pattern with teams that had a Silver Ranger as a Sixth Ranger, that now seems to be broken. The first team was Megaranger. The pattern seemed that the teams had to have a Black Ranger and
no Green Ranger. Megaranger and Boukenger are the only ones that had
Red-Yellow-Blue-Pink-Black-Silver. Gaoranger was
Red-Yellow-Blue-White-Black-Silver. Gokaiger seemed to break the Black Ranger pattern (within a six ranger team) with a
Green Ranger. But it is not the first team to have a
Green Ranger and a
Silver Ranger. Go-Onger not only had
Green, Silver, and
Black, also had
Gold.
UPDATED 10/13/11
Where I see the next decade taking us
I see the 00's as an experimental decade design and team wise for Super
Sentai, what with four teams starting in trios (Hurricanger, Abaranger,
Gekiranger and Go-Onger), compared to only one series per decade with
one trio prior (Sun Vulcan, Liveman and Kakuranger). The 00' also had more experimental color mixes like in Hurricanger and Gekiranger. For this decade,
Goseiger and Gokaiger so far are very standard. The 90's decade for me
is the norm, the level of what is expected and standard. The 80's for me
was also experimental, to figure out what is the norm for Sentai, with
Changeman with a color scheme that has yet to be emulated and Liveman
and Sun Vulcan with starting with three. And this past decade used less
pink rangers, much to die-hard fans' chagrin and probably little girls
who love PR. I love Pink and I love Pink Rangers but I understand where the use of less pink comes from. I think it is the idea that boys are what the brand is for and they don't like pink and don't want pink on their robos. Less female toys for the past years has stemmed that Super Sentai and Power Rangers by extension are for boys and boys won't buy girl-related toys. I think the main reasons girls are still in teams is for tradition and eye candy for boys and their dads. You might not agree.
Where I see the next decade going is maybe a bit more Pink Rangers than in the last decade but not as much as in the 90's. Also, I am hoping for some more use of purple and some gender changes, like most fans have been hoping for (female green ranger, male pink ranger, etc.). But we'll see. I also for see another Dekaranger, with 7 or 8 members, to sell more toys. Or something like Go-On Wings, with two 'sixth rangers.' But most likely two males like the Gouraijers. I also forsee less robos for some reason and more arsenal, like Kamen Rider. Those are my theories. I am guessing there will be more teams starting with three, probably something like Go-Onger did, it quickly becoming 5, in order to sell more toys. But this is my own speculation. In 5 years, I may look back at this and laugh. I am hoping for a 'Back to the Future' theme in 2015 since the sequel was set in 2015 (well some of it).