So the trial mode pretty much stumps me by the time i get to the third trial bit which involves cancelling moves
currently doing it with dhalsim, its a medium kick into a light yoga flame, ive tried different timings and i don't seem to be doing it at all, what am i doing wrong?

The timing can be really tough. Mostly, you just have to work on it. Sometimes a technique called negative edging can be helpful. This is when yo press a button to do a normal move, hold it down, then do the motion for a special, then release the button.

For example, if I want to do a punch into fireball with Ken or Ryu I can hit the punch button, hold it, do quartercircle forward, then release the punch button. Obviously you have to do this pretty quickly.

Hope this helps a little.

oooooooooooh, i was also stuck on ryu's 3rd trial, just tried that, took me a few goes to get the timing but i can totally do it now, thanks very much :D

Some of the combos in challenge mode are so difficult they take me 15 or 20 minutes to pull off even once.  Just keep at it, it's all practice and timing.

Im not really liking playing this game with a DS3 or SixAxis timing is really a bitch and blisters are too. I can still pull them off, but on the "trial hard" mode, its much harder. good thing i was able to order a good stick :)

I'm also finding it impossible to cancel.  I'm doing the trial mode with Sakura, and the first cancel move they want me to do is medium punch into hadoken.  The on-screen instructions list this as just medium punch followed by qcf+punch, but does canceling a move require dashing mid-move?  Should my move be medium punch and then a quick qcf+punch, or should it be medium punch, dash forward, qcf+punch?  I've tried both ways a few hundred times and haven't pulled it off either way.  How do you cancel out of the medium punch animation, Sakura's takes about 1/10th of a second?  Currently I'm blaming my problems on me sucking and also not having an arcade stick, but I'd certainly appreciate it if someone could explain this for me, if there's anything to be explained other than that it's just timing.  Thanks.

"I'm also finding it impossible to cancel.  I'm doing the trial mode with Sakura, and the first cancel move they want me to do is medium punch into hadoken.  The on-screen instructions list this as just medium punch followed by qcf+punch, but does canceling a move require dashing mid-move?  Should my move be medium punch and then a quick qcf+punch, or should it be medium punch, dash forward, qcf+punch?  I've tried both ways a few hundred times and haven't pulled it off either way.  How do you cancel out of the medium punch animation, Sakura's takes about 1/10th of a second?  Currently I'm blaming my problems on me sucking and also not having an arcade stick, but I'd certainly appreciate it if someone could explain this for me, if there's anything to be explained other than that it's just timing.  Thanks."

Awesome, thank you.

Just made a thread with links to everyone's trial mode:

http://www.giantbomb.com/street-fighter-iv/61-20456/all-character-trial-mode-links-normalhard/35-231469/#1

It helps to see the combo when done correctly.

Also here is a link to fighting game terminology. Might help explain concepts like cancelling, crossover etc.

http://en.wiktionary.org/wiki/Appendix:Fighting_game_terms