finally figured out how to insta charge...LOL
first of all, not all combos can be charged, usually its the square>X ones or one of the X chains(be it neutral, downwards or forward), if its a correct combo then pressing O will charge 1 gauge for you(plus the amount you gained through comboing, usually makes it looked like you've gained 1 1/2 gauges from it)
the timing isn't strict at all, you just need to find the right combos for them, right after founding out about this, i can say garren is one of the top characters in the game, mainly because he only need two fast hits to charge his gauge, and the kick is, its a gun attack(kaixa also only need two hits but its a close range melee)
EDIT: just played date birth today, the caterpliiar kick>insta charge thing was a riot, ditto with his ability to tack in insta charge after the >+X,X birth buster
also, a new(weird?) thing about decade's green gauge, whenever you enter climax time with its kamen ride copies, the song played would be of said rider instead of decade's theme(i.e it'll play kakusei or whatever theme you set for blade if you climax timed with the decade~blade form)
this feature makes decade less boring to play through arcade mode due to the music choices, but the gameplay nerf is still there, which kinda balanced it out
and lastly, the board is dead it seems, and we haven't even got black shroud's annual climax heroes guide yet...