Yeah.. I got stuck on that one for a while too.. you have to learn the pattern to kill the frogs.. its an arse.
From memory you want to be doing the 1st room in 10-11s.. the 2nd room you should have done in 20s total.. the 3rd room around 28s which will leave you with enough time to do the fourth room.
If you need some more tips, I can memorise most of the pattern I used.. but feel free not to read on if you want to do it yourself...
So as soon as you jump the first pipe, kung-fu kick the stilt frog which also kills the second frog.. run up plant, kill third frog, wall jump backwards, kill falling fourth frog, slam on the fifth (stilted) frog.. that should kill the other one too.. exit room.
Run left, kill frog, wall jump backwards until new frogs appear, slam on bones to kill 2nd frog, from the resulting slam, you'll bounce upwards, with that bounce kill 3rd frog.. jump on hook, kill big dude.. wall jump backwards to end wall, slam down, on the bounce upwards, kill 4th frog, should push it into 5th frog.. exit room.
Hit right stilted frog first, (you only have to knock him down - don't have to kill him - he'll die before you leave the room).. then kill 2nd frog on right, wall jump backwards to ropes, bounce on third frog (the other (normal) stilted frog), kung-fu kick the 4th frog and slam on the 5th frog, exit room.
This is where my memory gets a bit hazy.. but kill 1st frog, wall jump backwards.. get onto rope going left and kill 2nd frog - get back onto the rope going right, kill 3rd frog, get back onto rope going left kill 1st big dude, you must wall jump now otherwise shadow rayman will catch you.. back onto the rope, kill 2nd big dude, then wall jump up to the teensies.. you'll need to do 3 wall jumps quickly.. 2 wall jumps aren't enough to make it to the platform.