1

There are many people in schools which are available to help poor performing students do good.

There are many people in schools, who are available to help poorly-performing students do well.

Change good to well because it modifies do, which is a verb and so we need an adverb. Change which to who because there is a subject in the relative clause. Change poor to poorly because an adverb is needed. Add a comma before who because of the relative clause. Put a hyphen between poor and performing. 

2.

It is customary for everyone to raise when the star spangled banner our national anthem is sang.

It is customary for everyone to rise when we sing the Star-Spangled Banner, our national anthem.

Change raise to rise because you raise something and a person rises, rise is intransitive so therefore it doesn't take a direct object. Change sang to when we sing because we don't like to have verbs in the present passive. Put a comma after banner for the appositive.

3.

Most students completed there book reports on invanhoe long before prof parker collected it.

Most students completed their book reports on Ivanhoe, long before professor Parker collected them.

Change there to their because it needs to be possessive. Italicize and capitalize Ivanhoe because it is a long piece of art. spell out professor and capitalize Parker. Put a comma before long for the temporal adverbial modifier. Change it to them because the reports make it plural so them is needed in place of it. 

4.

Either you have got to go or me cause the team need at least one off us inorder to make the playoffs.

Either you or I have to go, because the team needs at least one of us off in order for us to make the playoffs.

Change either you or me to either you or I because i is the subject. Change off to of and add a space between in and order. Change cause to because and add off after us. Change need to needs.

5.

Mars attacks is a name of a funnier movie staring Jack Nicholson that is about them funniest looking martians whom attack the earth.

Mars Attacks is the name of a funny movie starring Jack Nicholson, which is about funny looking martians who attack the earth.

Italicize Mars Attacks because it is the title of a movie and also change staring to starring. Capitalize the "a" in attacks. Change that to which, they are both relative pronouns, but which is more particular than the general pronoun of that. Change funnier to funny because funnier is a comparative , but we are not comparing it to anything so funny is substituted. add a comma after Nicholson for the relative clause. Add another comma before who and change whom to who for the relative clause with no subject in it. Get rid of "the funniest" and change it to "funny" because its not in the superlative.