Much Weaker With Parallettes.

So I noticed I'm much weaker when doing exercises on the parallettes. My planches are way worse and I just can't seem to be able to press to a handstand. I can do a straight arm tucked planche to handstand on the ground with no trouble. I can do l-sit to bend arm press to handstand 3X in a row with no trouble too, yet I can't do one of them on the parallettes! How can I improve in this? I need this because I have to perform on the P-bars soon!

Work them on the pbars or paralletes. Only way to improve is to practice.

I also think that my adv tuck planche is a little weaker on parallettes. I feel like the reason is because they are too thin and that if i had some thicker wooden ones like gymnasts use that it would be more comfortable. 

If the parallettes are too thin to grip comfortably it will impair your ability to hold position. If your parallettes are of sufficient size and you rarely work your static holds on them, the issue is likely just that you're not use to holding on parallettes. The strength is not significantly different on parallettes versus on a flat surface, so if you work on it your parallette planche should catch up to your floor planche very quickly. 

Your sttength will transfer quicker than you think. Example: You can back squat 2x bw but cant perform a pistol squat. You might hqve the strength for it, but not balance. With some practice your balance will come and your strength won't be a prob. Same in parreletes, the only problem might be wrist prep. Depends on the person.

Yeah my wrists feel really weak when trying to do a straddle planche. Hopefully I'll improve fast.