☆ It really depends on how you know or deal with Kirby's bad match up's. Since you'll mostly see Meta Knight or Snake or most of the S or A tier characters at the matter, you have to know how to deal with them or pick a character that can deal with them better than Kirby, I'll list my top five characters that I think would fit the secondary for Kirby: ☆
King Dedede: King Dedede can able to handle a number of Kirby's even and bad match up's. Snake, Marth, Donkey Kong, Wario, ROB, Lucario, Mr. Game & Watch, and Zero Suit Samus mostly. The king can clean near all of Kirby's bad match up's. He's not hard to master if your use to Kirby.
Snake: Same as the King, but can handle Ice Climbers and Meta Knight much better, but a bit more technical.
Marth: He's easier to use, but hard to master. Any character that's not Meta Knight, Snake, or Donkey Kong, Marth can handle Kirby's bad match up's.
Pikachu: Able to handle Snake, Wario, and Ice Climbers for Kirby.
Toon Link: He's easily underestimated, also he can handle Ice Climbers, Wario much better than Kirby. Maybe Mr. Game & Watch.... I have yet to test this, but I don't think so.
☆ That's my thought's. If you know the match up's, Kirby doesn't really need a secondary to place well in a tourney, if you don't know the match up's, I would consider you to have a secondary that can handle his bad match up's. ☆
☆ Also, I love your avatar gopobox. =3 ☆