Dukemon22, the number 1 English source of Sentai and Kamen Rider rumors says the latest rumor of the 2010 Super Sentai will most likely center around cards. The rumor is that the arsenal used are Data Cards, that also double as a card game, much like Kamen Rider Decade. He says: "Not sure if the Sentai Data Cards will be compatible with Ganbaride, but Bandai not taking advantage of cross promotion is unlikely. Besides which, if they do another team up (New Sentai and Double, and maybe then Decade too), the cards would be a cool way to unite both shows." No word on colors used or numbers in team. Early rumors indicated on a 5-member team but the last rumor was three. Most likely animals will be used. Past rumors for 2010 have included ghost investigators, monsters used as allies (like Digimon Froniter), and combination of those last two concepts with Youkai.
Other rumor is that this new Sentai series will only last 30 episodes or so like Kamen Rider Decade. One of my personal speculations is that the Rangers will use RangerStrike cards like Decade did with past seasons OR they will use data cards like Kamen Rider Double and have multiple flash-drive-like devices.
"The rumor states that the villains this coming year, at least the first set of villains, will be an evil sentai [of 5 members]. The rumor also makes mention of a third sentai team, possibly extra rangers for the main team. This actually sort of reminds me of the setup of Digimon Frontier a bit, but with a Tamers flavor. Realistically, a card-based hero needs usually fights other card-based heroes, so this was sort of expected. It's like any other card game show."
"Now in my opinion, even though the cards are now pretty much confirmed to be in the style of Ganbaride. I think that the multiple teams, which have been rumored for a while, will take their motif from the different categories of Ranger Strike (Wild Beast, Earth Technology, etc.) Of course, that's assuming the rumor is true. Info from the reliable source from 2ch has provided info that Toei liked the "varied motifs" they used in Shinkenger, and will continue to mix and match in this coming year."
Rumored colors for the evil sentai: Blood, Iron-Blue, Black, Ash, and Tea. Maybe Tea will be close to yellow and Ash will be close to green, so it will be like a darker shade of Red, Blue, Black, Green and Yellow. Those of you that are color-blind, or various color visually impaired, you may not be able to see a difference between the colors I placed for black and ash.
Also rumor is that Shinkenger vs. Go-onger teamup will be released in theaters, like Go-onger vs. Gekiranger, most likely before March, but date not certain right now.
UPDATED SEPTEMBER 8, 2009 8:30 PM EST
"For all those still wondering, the use of cards by the Sentai '10 is pretty much confirmed. Details, of course, are not. However, we do have this latest mecha rumor, which seems to be saying that the rangers' mecha/partners will be very much based on different archetypes of TCG monsters. While Blue and Yellow are non-specific, many of the rumors have been claiming Red to be a dragon, though none of this rumor is anywhere near being confirmed. The card thing on the other hand, is pretty much a closed deal. I'm not sure of the team member count, but this rumor of three, opens up an interesting possibility. Even though the cards that are going to be used are supposed to be Data Cards, there's a chance the rangers themselves are based on the Ranger Strike categories." - Dukemon22
Here we could potentially have:
Red - Dragon (Mystic Arms)
Blue - Mecha Monster (Earth Technology)
Yellow - An Actual Existing Animal (Wild Beast)
The villains, rumored as evil rangers, could be Dark Alliance, and the eventual 2 additional rangers could be Over Technology.