6 neons--good
1 frog--good
1 fighter--good if its a non-aggresive betta
1 pleco--BAD they can get over 2 feet long
2 Angels--BAD they need at least a 30 gallon tank for a pair.
1 clown loach--BAD they get up to 12" in length
So, for a 16 gallon tank you could probably get 6 Neons, 2 frogs, 1 betta, and 2 Ottos (for a cleanup fish).
Thats about all that will fit... NO pleco, angel or clown loach!!
You should retrun those ASAP. As for the frog - an african dwarf frog = good... a clawed frog = BAD. Make sure you know which you have as the clawed frog will eventualy start killing fish.