I haven't seen the other thread (I did have a little look - could someone post a link to it please?)
My DD (also Y5) sounds a bit like yours! She 'always' seems to sit next to someone who is annoying in some way, and she's easily wound up by it.
When she was in Y3, the lad sitting next to her asked for her help so often that she fell behind with her own work. After a few months of this, I suggested that she simply said politely to him every time, "I need to get on with my own work, so you'll need to ask the teacher." Perhaps that was mean, but she wasn't actually his TA, and it was affecting her own learning. It solved DD's problem: the other kid was not her problem!
By Y5 your DD ought to be able to deal with this herself. I'd suggest your DD deals with each of the specific issues (rather than moaning generally about this annoying kid!). I'd suggest the following:
1) he copies her all the time
She should go and see the teacher and explain this, and ask whether it's ok if he copies 'all the time'. If the teacher says it's never ok, your DD needs to find out from the teacher what she should be doing about it. If it's sometimes ok, the teacher needs to tell her when those times are.
2) won't talk
Not sure what you mean by this, but if you mean that he won't talk when they're supposed to be doing paired learning, then when it happens she should ask the teacher what she should do with a partner that won't talk. She should try not to moan, but explain that she is getting no response and the shared task is therefore impossible, and should she do something else instead?
3) farts a lot (!)
I don't have a suggestion for this one. I think she'll have to put up with it.
4) leaves her to do all the work when they are supposed to be working together
If she's being honest about doing 'all' the work, then it's similar to number 2 - she should ask the teacher how to do the paired task when only one person is participating. Again, not in a moany way - maybe ask the teacher politely whether she can do the task on her own?
Basically, use this as an opportunity for your daughter to learn to raise specific issues calmly and constructively. The teacher will hopefully have some useful suggestions, and if it's not working and your DD persists in asking for 'advice', the teacher will probably change the seating plan anyway, for an easy life!