In Mario Baseball, chemistry actually affected the ability of of certain characters. Good chemistry like Mario and Peach means that they will try to impress each other at field or at bat. Bad chemisty like Luigi and King Boo means they can't stand each other. They'll do fine batting but on field, they're screwed. But why do some characters has bad chemistry with others. I will give my best explanation. Some will make sense others will kind of bizarre.
Mario has tension between Wario and Bowser
Wario- Well they are archrivals and while they can put up with each other sometimes (SM64 DS) That doesn't mean tension eases
Bowser- Do I really need to explain this?
Toad and Toadette has tension Bowser, Wario, and if I recall correctly I think Waluigi too.
Bowser- Well this is the guy who kidnapped your princess several times. Turned your people into bricks. Of course they hates the guy
Wario- I think Wario Woods has something to do with it. Toad was the hero there. Wario was the villain. They haven't forgiven each other since. Toadette is different story. I'll explain this later.
Petey has tension between Daisy, Piantas and Peach
Daisy- With Daisy I think its matter of her taste. She likes flowers. Even though Petey is a flower, he's a mutant freak and Daisy doesn't like that. Therefore Petey resents her as well. And I think it's the same reason with Peach as well
Piantas- In Sunshine, Petey attacks and casue quite a mess in Pianata village. He must not like them. As for the Piantas, they never forgave Petey for what he did.
Luigi dislikes King Boo, Boo, and Waluigi
King Boo and Boo- They tricked him into coming into a haunted mansion and scared ahlf to death of course Luigi doesn't like them. And for some unknown reason, King Boo hates the Mario Bros. Also, Baby Luigi isn't fond of them either.
Waluigi- His arch rival. I don't have much to explain since Waluigi and Luigi never been in canon game
Bowser has tension between Peach, Mario, Baby Mario, and Daisy
Peach- Bowser has a crush on Peach. And he kidnaps her for that and to rule her kingdom. This cause Peach to show dislike for him. Bowser's not happy with that.
Mario- Do I really need to explain this?
Baby Mario- Well Mario has been thorn in Bowser's side since his birth. Of course he hates his younger self too.
Daisy- I don't have any way to see this. The only I see why Bowser and Daisy don't like each other is because of what happens in Mario Party 3(which is quite funny btw)
Wario has tension between Mario, Peach, Toad, and Toadette
I already explained everyone except Peach and Toadette. But I think Peach just sees Wario as nothing more than a big, disgusting jerk.
Toadette- She has interesting relationship with Wario. Now you might say they have bad chemistry because of Mario Baseball but that may not always be. In Mario Party 6 (I think 7 to but I don't have the game) When Wario and Toadette were in a team together, their team name was called "Secret Friends." Could it be that they fake their comtempt?
Baby Mario and Luigi dislikes Shy Guys. Throughout Yoshi Island, Shy Guys been trying to get them. Therefore, they're afraid of them
Waluigi has tension between Luigi, Daisy, and I think Toad and Toadette
Luigi- See Luigi's section
Daisy- I don't for sure. I've heard that Waluigi has a crush on Daisy but she doesn't return the affection.
Toad and Toadette- I don't know really. Maybe because of Toad's and Wario's tension
I'm going to find more. Will somebody tell me who else has bad chemistry with each other in Mario Baseball? And also, I'm going to find out how are some characters are rivals.