I'll try my best to analyze all the characters you have shown me
Bayonetta- She does not rely on projectiles and is widely considered a top tier, she has some easy combos and is easy to pick up but as the scene gets more advanced there is more reads that tech with the character, she is probably my recommendation for you to use. She is very combo heavy and has a great matchup spread witha versatile recovery just takes a while to get the hang of.
RosaLuma- I would not go with character unless you have some serious time. Extremely good character would be a good playstyle mixup but unless you want to spend a lot of time in the lab I would not put RosaLuma as a secondary.
Mewtwo- Also I would recommend his, lots of kill options, light weight solid pick I would recommend this character as well.
MetaKnight-MK is my co main and I love to play him, good recovery, combo heavy, can have some trouble killing, he will take a lot of practice, but I would not recommend him as a secondary.
Corrin- Corrin has a lot of range and not really very many true combos what from what I know, he has a beast counter (best aerial counter in the game his spacing and quick projectile make him an adequate zone. Solid pick if this is someone you like. And you can only play female Corrin male Corrin is not allowed.
Pit-Pit is well known for being an honest character with a basic projectile and a reflector, he has some good range and he has some disjoints on his moves. Very good pick if you want him go for him.
Lucario- Takes a lot of practice with his arua and his strings, very good character not all that complicated but I would not choose him for a secondary.
Ness- Good aerials, 2 anti projectile moves (f smash and PSI Magnet) The recovery can be a bit ehhhhhh.... very good character easy to learn as long as you can deal with his recovery
Robin- Super complicated lots of situational awareness, he is not a great secondary (unless you are Nairo) also I would not use another projectile based character for previously stated reasons.
Lucina- I would just use Marth and Lucina together, they would be a good pick however I would pick some better at approaching and not so much a Zoner as a secondary.
In short I would reccomend the characters you have given me in this order for you to use as a secondary: Bayonetta, Mewtwo, Ness, Corrin, and Pit.
Let me know what you think and If you want I could run a more analyzed post on a shorter cast of character you think are good options like maybe 2 or 3 of them.
Oh and maybe should drop the Villager as well and use Mario, gives you a reflector, Mario is much easier to learn, and very viable for competitive play and would mix up your playstyle as well.