Hi rene.

to the forums!!!
Firstly, I would get rid of that pleco. They produce a lot of waste, and a 6" pleco in a 10G tank is just too much IMO. A 10G tank is not suitable for any pleco except for zebras and clowns perhaps. And you need to keep more than 1 zebra pleco in a tank, so I'd really not get any pleco for a 10G. Any idea on what kind is it? If it is a common pleco, then you better get rid of it fast. Don't mean flush it down the toilet, see if your lfs will accept it.
I know it's hard because they look so

, but I made the same mistake as you did when I first started out. Once I returned it to the lfs, I could see a MARKED improvement in the water clarity, as well as the amount of waste I had to vacuum every week.
Secondly, zebra danios need to be in schools of 5 or 6, and in a tank that is 20G or more, as they are active fish and need the swimming room. That is no doubt.
Don't really know much about dwarf flame gouramis, but if they're the same as dwarf gouramis, then you should be alright. So go with the gourami as a centrepiece fish or whatever you call it, and get a small school of fish in addition.
Say White Cloud Mountain Minnows perhaps? Maybe 5? I have 3 in my 10G tank, and they are doing wondefully well! And they colour up BEAUTIFULLY once you keep them at home for a while and give them a good diet and all that... Gold and red, just amazing. I could sit and watch a school of them in a large planted tank for hours...
Then if you really want, you can prolly. keep a trio of ottos in there for algae. I promise you'll see more of them than the pleco, and they interact with each other very well. So that's why I recommend you get more than 1. Less waste too and you don't have to feed them much if you already have some algae in your tank.
The inch per gallon rule is not hard fast, as you can't keep a 10 inch fish in a 10G tank. It's a pity that many beginners (including me) thought this rule was one I could live by. Definitely not the case....
The size of the fish matters more I should think, and the amount of waste they'd produce. Also, a lot depends on the tempremant of the fish and whether it will claim territories or not.
HTH.