I don't see myself getting into an ivy league from high school because of how much I slacked off the first two and a half years of school (I'm in grade 11). My marks were decent, 84-86 average, but I also had/have no extra curriculars (except for self-taught guitar since I was 11, I play a lot).
However, I'm putting more effort now, and will finish this year with a 90%+ average (been getting 97-100 on everything since new year). I also plan to volunteer at a hospital over the summer, I'll join a couple clubs in grade 12, and should finish grade 12 with a 95%+ average without much trouble.
Still, I understand I won't get into an ivy league out of high school, but what about after 2nd year university? I was thinking of continuing to put the effort in and get amazing marks at either University of Toronto or McGill University, along with a lot of extra-curricular stuff. If after a year or two of this, would it be possible for me to transfer to an ivy league in the US? Columbia, Brown or other?
If that's not possible, what about after earning my bachelors (either engineering, physics, or pre-med), would I have a chance of getting into a good ivy league graduate school?