Gate-

Nationality-

Candidates of Indian nationality will be eligible to appear for GATE 2020.

Candidates from countries other than India will be also eligible to attempt GATE 2020.

Academic Qualification-

Candidates must have passed graduation in engineering/technology or Master’s degree in any relevant science subject.

For more information, you may refer to this-

https://engineering.careers360.com/articles/gate-eligibility-criteria

GRE-

GRE doesn't have any specific eligibility criteria. You may refer to this for more information on the examination-

https://studyabroad.careers360.com/articles/gre-eligibility-criteria

TOEFL-

It is just a English test and any candidate can pursue it. Here are more details-

https://studyabroad.careers360.com/articles/toefl-eligibility-criteria