Hello aspirant,

No exam is  Hard if you work hard 

After 12 these are tha exams where many students feel tough

• JEE advance
• JEE mains
• BITSAT
• VITEEE
• COMEDK
• IPU SET
• MANIPAL
• AMU
• NDA entrance exam with (PCM) And
• State level exams like MH CET, AP EAMCET,TS EAMCET etc.

All the above mentioned is for engineering field

For medical 

• NEET
• JIMPER
• AIIMS
• CMC -VELLORE
• MANIPAL

Hope above information is helpful to you

If you have any quire's please let me know

Thank you