First of all, beating Ike head to head doesn't mean that Lucas is a better character than Ike, at all. Ditto Luigi. All that means is that Lucas wins the MU. Secondly, you cite your win vs Ryo. How many times did you beat him? Were they close? Does Ryo have extensive MU exp vs Lucas (you said you do have exp vs high level Ike play)? Etc etc. There's a lot more that goes into a MU than singular events that happen.
While it's great and all that you do well in locals and that you managed to beat Ryo at Apex, but you also said that you don't do as well in nationals due to running into a "high level Snake." If a character as common as Snake is enough to cause problems for Lucas while Ike has a manageable time in an actual important MU (read: not the head-to-head vs Lucas), then it's more supportive of the idea that Ike is a better character.
Going on to your opinion of MUs and your win/loss records vs characters:
Once again MU (in)experience has to be considered as a factor. You said that you beat a lot of ROB's except for Stingers with whom you go back and forth in wins and losses. This seems to imply that you beat the other ROBs due in part for them not being well versed in the MU while Stingers, who is after playing you frequently, does significantly better. This doesn't mean that Lucas beats ROB at all, it doesn't mean they go even. All it means is that you beat people that lacked exp in a MU and go even with someone with exp. All the while, the person you go even with, while a great player and an amazing ROB, still isn't the best ROB. Same thing applies to IC.