What rules govern the use of was and were? Some people use was and some use were...
"The two dogs were both at the show"
"The text for these was used as contact details"

There is no leniency here at all. The answers are:

"The two dogs WERE both at the show"
"The text for these WAS used as contact details"

Plural (two dogs) = were

Singular (text) = was

The second point is related to prepositional phrases.