>>7146040161 doesn't have gimmick characters, but 2 has a twist in the prologue that makes the Monokuma-like creature in this game a gimmick character, rather than the mastermind. As I said, it's a twist in the prologue, but I'll tag it all the same One of the students is revealed as the actual mastermind behind everything in the first 30 min of the game. The Monokuma of this game is second to their authority.
>>7146040971 has a male MC
2 has a female MC, but she's such a blank slate in the beginning that it barely affects the plot
while you can play them out of order, I'd highly recommend playing 1, then 2, since they share lore and characters. The translation in 1 isn't so bad that you should skip to 2.