Well, I've picked up Bayo since day 1 and began maining her since April for tournaments. I've won locals with her, and top 5d regionals. Albeit, some matchups are painful. For instance, Pikachu (as you point out) is a pain. For specific matchups, I use my previous main, Zero Suit Samus.
These matchups are:
Sheik, Pikachu, Cloud, Ness, Sonic, and Ganondorf.
Some of these are because of the sheer speed of ZSS (Sonic, Sheik and Ness). Some of these are because its impossible for Bayo (Pikachu and Cloud I believe). And Ganon because I can keep him ways away with ZSS Spacing. I also use ZSS for other matchups, but thats just when I'm feeling it, or the other person has read my Bayo matchup.
For Example, Yesterday in a local here, in grand finals ( I was in winners' side), I was playing a Captain Falcon / Corrin Main. Game 1, Bayo vs CF, I won. I changed to ZSS to prevent him from learning any further from my Bayo, and to get the counterpick advantage. He won Game 2, but I won Game 3 and 4 with Bayo. Since both characters have different things you have to be worried about, the mixup is just perfect.
Hope this gave you some insight