• Not willing to come in even 5 minutes early or stay 5 minutes late

Not everyone is. This will be factored into his performance reviews. NOT YOUR PROBLEM; accept it and move on

• Evading contact while working from home

Judgmental. You don't know if he is "avoiding" or just highly focused on what he is doing and not accepting interruptions. WRONG FOCUS; if you need him to respond within a specific amount of time ask your manager if that is a reasonable expectation and if so could the manager take it up with him. Be sure you have logs of every time you reach out and how long he takes to get back to you, or this may be dismissed as a biased reaction... and because that gives the manager a concrete basis in which to say either he's being slow or you're being unreasonably impatient.

• Claims a task is done, while a review by a coworker shows the result lacks required level of quality.
• Claims a procedure is safe, while a review shows that he spent only minimal time to do the necessary research - much less than required.

Have you worked with him to help review his code and teach him how to avoid these errors? Nothing should be committed to the code base without at least an opportunity for review. Nothing should be committed without running existing regression tests and writing new ones as necessary.

• Refuses to share information

Refuses, or doesn't know how, or doesn't understand that it's part of the job? Again, education may be what's needed, along with requirements that design and implementation be documented.

• Oscar doesn't convey the message accurately and clearly.
• Oscar makes inaccurate or misleading statements to outside parties.

Again, sounds like he's a bit out of his depth and needs education in how to take a complete and accurate problem report, and in how to communicate with customers (including learning to say "I'm not sure, but I'll get you that answer" rather than guessing). Or needs better language skills. Or should not be assigned customer-facing tasks in the first place. Don't just complain about his weaknesses; figure out how to address them or avoid them.

You have a great opportunity here to build your reputation as a mentor. And if you tell your manager you're doing this and he an show so e success it will look great on your performance evaluation. But that starts by recognizing that rather than just complaining you need to actively engage, guiding and teaching, and need to exercise some patience and compassion in the meantime. Plus making sure the individual is assigned tasks not too far beyond their capabilities.

This is all assuming your description is accurate. You probably want to run this by your manager and get the mentoring role made official before meddling too much.

• Not willing to come in even 5 minutes early or stay 5 minutes late

Not everyone is. This will be factored into his performance reviews. NOT YOUR PROBLEM; accept it and move on

• Evading contact while working from home

Judgmental. You don't know if he is "avoiding" or just highly focused on what he is doing and not accepting interruptions. WRONG FOCUS; if you need him to respond within a specific amount of time ask your manager if that is a reasonable expectation and if so could the manager take it up with him. Be sure you have logs of every time you reach out and how long he takes to get back to you, or this may be dismissed as a biased reaction... and because that gives the manager a concrete basis in which to say either he's being slow or you're being unreasonably impatient.

• Claims a task is done, while a review by a coworker shows the result lacks required level of quality.
• Claims a procedure is safe, while a review shows that he spent only minimal time to do the necessary research - much less than required.

Have you worked with him to help review his code and teach him how to avoid these errors? Nothing should be committed to the code base without at least an opportunity for review. Nothing should be committed without running existing regression tests and writing new ones as necessary.

• Refuses to share information

Refuses, or doesn't know how, or doesn't understand that it's part of the job? Again, education may be what's needed, along with requirements that design and implementation be documented.

• Oscar doesn't convey the message accurately and clearly.
• Oscar makes inaccurate or misleading statements to outside parties.

Again, sounds like he's a bit out of his depth and needs education in how to take a complete and accurate problem report, and in how to communicate with customers (including learning to say "I'm not sure, but I'll get you that answer" rather than guessing). Or needs better language skills. Or should not be assigned customer-facing tasks in the first place. Don't just complain about his weaknesses; figure out how to address them or avoid them.

You have a great opportunity here to build your reputation as a mentor. And if you tell your manager you're doing this and can show some success it will look great on your performance evaluation. But that starts by recognizing that rather than just complaining you need to actively engage, guide and teach, and need to exercise some patience and compassion in the meantime. Plus making sure the individual is assigned tasks not too far beyond their capabilities.

This is all assuming your description is accurate. You probably want to run this by your manager and get the mentoring role made official before meddling too much.