I'm doing a show, and i wanted a certain role that i believed I could pull off very well. However, was cast for a different role. I still believe that I can do very well as this role. But, the person who got the role i wanted doesn't have the skills to pull it off well.
I really wanted this role, as it's my last show with these people.
I don't think that the guy who got the role is up for the challenge of the role
What do I do? I'm planning to watch this week of rehearsals and see how he does before confronting the directors about my worries

I am understand your concerns. Normally I’d say that it might have nothing to do with you, and that the director is trying to give this person a chance to grow by stepping into it. Given that this is your last show with them though, I understnd completely why this is a special case. Is it his last show too by chance? Well, to the paractocal advice. It’s worth speaking to the director in a non confrontational way. For whatever reason the director cast him, so either the guy has what he’s wanting for the role as director, or there’s another reason. So don’t start from the angle that you think he can’t handle it. Ask him why you didn’t get the role, let him know you really wanted it and why. See if there’s anything that can be done. Don’t attack his casting choice directly, but communicate your thoughts. Watch how things go over the next week and if you still have concerns then yeah- bring them up if you’re not satisfied with the results.

I agree with Guest. Roles are tricky because everyone perceives a character and how to portray them differently, while you think this guy can't pull it off and is playing this character "incorrectly" he may believe he's doing a great job. I know how it feels to get a different role than wanted for your last show, it is frustrating because you wanted to show your potential but you still can. You still have a role which means you can give everything you've got into the character you are currently playing. Maybe someone who wanted your role is watching you thinking "I could do it better", it's about perspectives sometimes, especially in cases where you don't have much of a choice. Talk to your director in the way Guest suggested and maybe also give some advice to the guy playing your wanted role, don't give it directly, maybe ask why they do the things they do and it might give you some insight into why they're acting this role differently then you believe it should be acted.

This is my last show, however this guy has a few more years. I've seen this show before, so i know how the character acts.
I know I could really get this chatacter down very well and I've worked with this guy before. He goofs off the entire time, he barely learned his lines for the last show (he had max of 15 short lines) and for this show we have half the rehearsal time abd he has nearly 40 lines

Don't know why you deleted those last comments but anyways, talk to your director, see their point of view. If you can't make a change then I suggest focusing on your own character and getting that nailed then maybe helping this guy out with his method acting and maybe giving him some gentle pointers or even helping him rehearse his lines. That way you could influence his character through your advice and own impersonation of it.

I deleted them because I felt that it was being too mean towards him. He isn't bad, he just doesn't put in the same effort as the rest of us.
Thank you, I'm gonna talk to one of the directors.
Thank you, i know this was really just me complaining sorry.

I get it, the same thing happened to me this year, its also my last year with the people producing the show. Have faith in the person and your directors, there's always a reason for the directors castings.

Okay! So. After hearing this guy read through the lines, he's changed alot from the last show.

Hopefully in a good way? I wonder, given your assessment of his personality, if the director sees potential to be fostered, and believes that the responsibilities or weight of this role will help him bring them out? I’d still say talk to the director, even if he’s doing well. You don’t have to talk about him, but maybe (if you’re willing and able), ask if you can understudy they part while doing your role, explain the importance of your final show and see if he might give you one show in the role. Unless you’re now content with things as they are, in which case, even better since that requires you to not do anything else!

I'm okay. The big musical at the end of the year will be my goal