I can safely tell you Ike is on the lower end of the tier spectrum, unquestionably in the bottom 20. If you want to dedicate your time to this character, understand several key things.
1) Never waste a move. Anything you do can be punished. You can't throw footsies out there, as some fast characters, like Captain Falcon, can - and will - punish you from a distance. Conserve your moves as much as possible.
2) Play walling. Edgeguarding is Ike's forte. It keeps enemies from camping him and maintaining stage control. Know your Nairs - reverse and forward - Fairs, and autocancel retreating Bairs, as well as when to ledge hog and when to edgeguard off-stage.
3) Positioning vs. damage. I've learned that it's more important to throw your enemy off the ledge than prioritize UThrow Fair combos. The latter gives your opponent an easy opportunity to come back on stage for free. Ike's lack of mobility makes him a poor landing-catcher, his dash attack being the only exception. If you're centerstage or attacking below 60%, UThrow Fair. If it's high damage, offstage.
4) Know your character weight and floatiness. Rosalina, Ness, Lucas, and Yoshi are among several characters who will no longer be affected by your combo past 60%.
In the current meta, the top players know this matchup and know exactly how to exploit him. They know how to spike Aether and throw large hitboxes out to kill Quick Draw, rendering your recovery nothing short of poor. The less your opponent airdodges, the less opportunity you have to get any damage.
If you're looking for tournament wins, I cannot stress avoiding Ike enough. You may as well play Zelda or Charizard. But if you're looking to play him because he's fun and fits your style, I can't stop you. Just keep the above in mind.
Also, Diddy and Sheik are his 30:70 matchups, with Meta-Knight, Cloud, Greninja, and Donkey Kong being next. Depending on your region, you may or may not have top players that will exploit your character and pick him apart. I wish you best of luck.