Globe approves postpaid plans and does not discriminate whether you are a student or not (just if you are from a call center in which case you have to prove that you have been employed at least 2 years ).
They do check your source of income or whether your capability to pay over the period you are applying for.
The trouble if you say from allowance is that they may question the future flow of it since it is an informal source of income and could be cut anytime without any legal implication.
Realistically, you can have better chances if someone with better credentials apply for you or if you lack documentation for your source of income, either pay 7 months in advance or have a Globe subscriber of good standing act as a guarantor for you.
A credit card is NOT necessary but would be helpful as Globe would just pass on whatever liability you have to the credit card company in case you use it to pay them off specially in an auto debit arrangement.
Similar to bank credit evaluation upon applying for cash loan or applying for a credit card, one has to establish his/her credit worthiness.
Globe needs to determine one's capacity to maintain and pay for the services and device, having a credit card (principal) is an advantage.