On paper, you don't handle Sheik.
In practice, you sometimes just have to make a wild guess with U-smash. The cooldown on that move isn't too bad, and it can be important for catching her out of the air and covering dodges.
The other tools that you obviously should be using in this matchup are Jab, D-tilt, and N-air and try your best to bait her into attacking you. Sometimes even if it's not safe to approach, you should try to attack her a few times to try to condition a response of some sort.
In my opinion, the most difficult part of this matchup is actually just surviving offstage. Sheik can cover options a lot better than most characters off the stage, which can be rough against Ganon's recovery. Be especially wary of Bouncing Fish as you near the blastzone, as Sheik is very capable of cheesing you with it if you aren't expecting it and don't airdodge at the right time. Bouncing Fish also can cover ledge stand with its lingering frames, so be careful as you get up from the ledge.
Once you survive past the point where Sheik can combo you across the stage, the matchup becomes more tolerable as long as you avoid gimps. You can always end Sheik's stock much earlier than the other way around, especially with Rage boosted tilts.
