Formal:
* Il est mon ami. (He is my friend.) - This is the most common and neutral way to say it.
Informal:
* C'est mon pote. (He's my buddy.) - This is a more casual and familiar way to say it, used with close friends.
* Il est mon copain. (He is my friend.) - This is also informal, but slightly less casual than "pote". It can also be used to refer to a boyfriend, so be mindful of the context.
For female friends:
* Il est mon ami. (He is my friend.) - This is the most common way to say it, regardless of the gender of the friend.
* C'est mon amie. (She is my friend.) - This is used specifically for a female friend.
For male friends:
* Il est mon ami. (He is my friend.) - This is the most common way to say it, regardless of the gender of the friend.
* C'est mon ami. (He is my friend.) - This is also used for a male friend.
Remember to adjust the level of formality based on the context and your relationship with the person you are talking to.