How are Gertrude and Ophelia strong characters in Hamlet?I need 2 solid arguments proving that Gertrude and Ophelia are not frail but rather seen...

There is evidence that both Gertrude and Ophelia are
stronger characters than they might be given credit for if one only gives their
character roles a cursery reading.  If you look at Gertrude, it is easy to assume, like
Hamlet and King Hamlet do, that she was too easily won over to Claudius by "the
witchcraft of his wit... that has the power so to seduce."  But that logic assumes that
Gertrude doesn't have anything to gain from the marriage.  While it is not stated
directly in the text, it is possible that Gertrude married Claudius to
maintain herself as Queen of Denmark -- a position I would assume
she loved having.  She may have married Claudius because it was a good political move,
preserving the throne for her son to take over eventually, while maintaining the power
of Denmark with a smooth transition of leadership.  Perhaps she married Claudius because
she still felt like a sexual, sensual woman who wasn't ready to wear widow's clothes and
be cast aside into a lonely room in the castle for the rest of her life.  All of these
possibilities suggest a powerful woman, not a weakling.  If you read Gertrude's
character with that sense of self-determination and putting Hamlet as a foremost
concern, then you can see another side of her.

As for
Ophelia, she is in a slightly more tenuous position in society.  She is an unmarried
lady who should protect her reputation, and must remember that she is a unmarried woman
still living in her father's home.  She obeys her father's command to put aside Hamlet's
affections, but she doesn't have much of a choice.  During his questioning of her she
does her very best to defend and explain her relationship with Hamlet, but he cuts her
off at every chance and insults her intelligence and her feelings.  Even though she
acquiesces to her father, she still tries to be there for Hamlet.  She is devastated at
his seeming craziness.  She seems to play into (or she staunchly rejects) his bawdy
flirting at the play-within-a-play (depending on how you read it.)  She does end up
committing suicide, but she has been through so much senseless tragedy.  With Ophelia,
you must remember that her position in society makes her weak -- not her personality
alone.