Short version:  
The mane cast objections if they were the player characters of Dangan Ronpa.
 
There were other objections that I wanted to make for them but they felt better suited for counter argument (NPC) objections from the game’s sequel. If you think there are other variations of objections the mane cast should say, I would like to see them in your comments.
 
Long Version (Very, VERY LONG):  
In Dangan Ronpa whenever the main character makes an objection he always says “You’ve Got That Wrong!” to the contradictions he hears in the class trial of this game. One of the main features about the game is the class trial that happens when one of the 16 students (You/Naegi included) follows the rules of killing someone to get out of the school they’re all trapped in, the rest of the students have to conduct an investigation and then hold a trial to figure out who the murderer is. If the other students manage to figure out who the murderer is and point them out, then the murderer will be executed, but if they don’t and pick the wrong person then everyone but the murderer will be executed and the murderer will go free, so the stakes are pretty high.  
Anyway, during the class trial’s nonstop debates when you notice something strange or a contradiction you make an objection with the right evidence, just like Phoenix Wright in a way. But instead of shouting OBJECTION like him, the main character says “YOU’VE GOT THAT WRONG!” instead. Also, if you spend time with some of the characters before they die you’ll gain special skills that will help you out a lot in trials, like the power to take less damage if you make a mistake or increase your life during trials, for example.
 
Later, in the sequel, the new main character says different things besides just “You’ve Got That Wrong” I found out about that from objection fandub exhibition of all the characters from the sequel making their own objection. Although I found out later that most of the stuff the voice actors say for the characters were made up but it was so good that inspired me to make this picture anyway. So this is what I believed what the mane cast will say if they were the main characters of a Dangan Ronpa game. Also, I had an additional objections for Spike, Twilight, and Rainbow but couldn’t fit them into the picture because the computer won’t let it be wider than it already is. Also, regarding the other versions of objection, I’ll try to find a way to make another pic that consists of the mane casts and other characters making counterargument objections and explain it sometime later. Anyway if there were other things the mane cast should say, I wouldn’t mind reading it in the comments. (Especially since I had hard time coming up with a couple with Applejack and Pinkie Pie).