Much like Chun-li or other such characters you have a lot of anti airs but they are all situational.
Play around in the training room with st.HP, f.MP and f.LP.
St.HP is your best anti air to deal with things like Ken cross up Hurricane Kicks. Keep in mind it’s kind of slow at 8 frames so it’s tricky to use.
f.LP is your quickest anti air at 4 frames but does little damage and has to be used pretty late to catch people. It has a decent hit box to deal with mid range jump ins. And while the f.lp does little damage in itself it leads to an air reset that you can take advantage of with a mix up of your own.
f.MP destroys most far jump ins because it lowers Hakan’s hurt box so much. Works a little better when oiled. You can also use f.MP on deeper jump ins because you will duck right under the attack. If you are quick enough you can catch them during trip guard for a oil rocket or U1.
Some less used anti airs that I find myself using a lot is st.MP and cr.MP.
I use st.MP against a lot of neutral jump attacks that are a bit further out. Sometimes will trade but in my mind that’s okay because Hakan is pretty weak to neutral jump pressure I find.
cr.MP is use vs characters like Rufus and Yun. I do crouch techs with cr.MP or just use cr.MP to beat dive kicks. Serves the purpose for me but maybe others use something different.