The Tetras are Skirt Tetras...I find them to be hardy, but nippy. The Guppy hiding out sounds stressed.
10g does not give a lot of room for getting away.
Do you have plants ?
Most Tetras and Cories do best in groups of 6 or more. A 10g doesn't have room for that unless you do Nano species (1" or near that as adults).
Consider returning Tetras and adding something that won't pick on Guppies.
Skirt Tetras can get 2.5"
If you really want the Tetras, maybe return the Guppies
and Cories and just do 5-6 Tetras. But even that is pushing it IMHO
I prefer a 20g minimum for all "Glo"'species. Zebra Danios are super busy and need room.
A 10g is marketed as a beginner tank...but most fish don't fit it long term.
I love my 10g. But I do Shrimp tanks or a Betta or Nano species.
I hope your fish mellow out.
Enjoy your tank no matter what fish you end up with.
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