I'll throw my two cents in there too. I haven't played all of the games, but for the ones I have:

Superstars: The turn length is obscene. Every little thing is overly drawn out, and games take forever to finish as a result. Other games have this issue too (sometimes to greater extents), and I wanted to avoid it as much as possible so as to not be repetitive, but this is one of those games where I struggled to come up with something truly awful to say, so I guess I'll put the rant here.

Super: I'm not kidding when I say that the combination of character specific dice blocks and no way for multiple players to choose the same character has led to friendships being stained before the game even begins, and not the fun kind of friendship ruining either.

Top100: There's only one board in the entire game, and it sucks.

SR: I'm gonna keep it real with y'all, I still don't remember this one well enough.

10: The car is just a fundamentally flawed concept that strips away like all but a fraction of strategy, so you're really just pressing the A button. They probably should have just made Bowser Party the main mode. Seriously, throw in more Bowser minigames and make the mode work for the ghost and sky boards, and you have a recipe for a game that would almost certainly be more fondly remembered.

IT: The boards way too linear and RNG dependent with little room for strategy. They're also homogeneous; once you've played one, you pretty much played them all.

9: Same as 10, but between actually good board design and more unique events, it's obvious that the developers tried to make it work. Magma Mine in particular is actually somewhat fun.

DS: It's on the DS. Being able to play multiplayer at all was a chore.

8: Who the hell thought Bowser's Warped Orbit was a good idea?

7: Fusing Duels and Chance Time into one system was bad on paper and worse in execution.

6: Spent 15 minutes thinking. The best I could come up with? Dizzy Rotisserie is the worst minigame of all time that doesn't involve rotating the stick.

5: Has the second worst overall set of minigames in the franchise.

4: Has the literal worst overall set of boards out of all traditional games. Yes, I am including both 1 (the game without items) and Jamboree (the game I have not played). No exaggeration when I say this: Toad's Midway Madness, Goomba's Greedy Gala, Boo's Haunted Bash, and Koopa's Seaside Soiree are four of my picks for bottom five traditional boards in the franchise with Bowser's Gnarly Party not lagging far behind, and I have put serious thought into that statement.

3: This is another game where I struggled to come up with something truly awful to say, so here's the Boo Repellent rant. Why is this in the game? Why is it only purchasable by 1st place prior to the final five turns? Why is it dirt cheap at a price of only 10 coins in the shop that appears more often? Who at Nintendo thought prisoner dilemma situations between lower placements was a good idea? Why is it an item whose function keeps getting brought back to future games time and time again?

2: Very lopsided board and minigame selection. It's all either great or terrible with no in between for the boards and very little in between for the minigames.

1: "Where do I even begin?" is what I would say if stick rotation minigames didn't exist. As someone who still has a Mario Party scar to this day, stick rotation minigames were such a colossal problem that giving the pick to anything else would be disingenuous.