To start, here’s proof that i don’t think Kid or Killer are fodder. This is from months ago, when Killer was being derided as fidder from all quarters
Now, as to Kid being a rival to Luffy, he fails for two very simple reasons
-his crew is not anywhere near strong enough to fight Luffy’s, let alone all the allies Luffy can assemble
-the two have never actually fought each other and are as good as allies.
1. Luffy
2. Marco
3. Kid
4. Zoro
5. Law
6. Killer (oh ho, controversial)
7. Sanji (probably also controversial)
8. Jinbei
9. Inu (counting Su Long)
10. Neko (equal to the above, ditto)
11. Denjiro
12. Ashura
13. Kawamatsu
14. Kine'mon (after here I stop really caring)
15. Izo
16. Brook
17. Franky
18. Robin
19. Kiku
20. Raizo
21. Nami
22. Ussop
23. Chopper
24. Carrot
25. Shinobu
2. Marco
3. Kid
4. Zoro
5. Law
6. Killer (oh ho, controversial)
7. Sanji (probably also controversial)
8. Jinbei
9. Inu (counting Su Long)
10. Neko (equal to the above, ditto)
11. Denjiro
12. Ashura
13. Kawamatsu
14. Kine'mon (after here I stop really caring)
15. Izo
16. Brook
17. Franky
18. Robin
19. Kiku
20. Raizo
21. Nami
22. Ussop
23. Chopper
24. Carrot
25. Shinobu
-his crew is not anywhere near strong enough to fight Luffy’s, let alone all the allies Luffy can assemble
-the two have never actually fought each other and are as good as allies.