I think what you want to say is "He (often) mistakes Tom for Tim" and "He confuses football with cricket".Can we say "He considers Tom Tim" or "He considers Football Cricket"? Or do we need to say "He considers Tom as Tim" or "He considers Football as Cricket"?
They are incorrect because they mean that in each case the person is mistaking one thing for another.He considers Tom to be Tim because they are twins.
He considers Football to be Cricket because he doesn't know anything about sports.
Are these still incorrect?
They are incorrect because they mean that in each case the person is mistaking one thing for another.
The word 'considers' rules out that idea: it implies that the person knows what each person or thing is.
You can say 'He mistakes Tom for Tim' or 'He confuses Tom with Tim' (when speaking about the person's habitual practice).
You can also say 'He thought Tom was Tim' or 'He thought football was cricket' (when speaking about a particular occasion).
I suggest that you open a new thread for this use of 'consider'. It's different from the OP which uses 'consider' in an unacceptable way.Can we say "He considers Tim his best friend" or He considers Tim to be his best friend" or "He considers Tim as his best friend"?
They were misusing the word 'consider'. That might be called a semantic error or I suppose a syntactical (i.e. grammatical) error.But those were not grammatically incorrect. Am I correct?