IF you have 6 Tiger barbs - and you need at least 6 to try and avert aggression - one shark, and a pleco (I think you mean a Bristlenose), your tank will be fully stocked. All these fish will probably be very small when you buy them, but the Tigers grow to 3", the shark to 6" and the BN to around 5" = 29" of fish total!
If you want some variety, you could get 3 Green or Albino tiger barbs, and 3 regular colour.
You must put
driftwood in the tank for the pleco to munch on and to hide in, and give the shark some sort of cave at one end of the tank.
Strongly agree with no Dwarf gouramis with Tigers.