I find it impossible to dislike the Monster Pit in this game. So much of it was done so well! Of course, gotta love the announcer and Morrie himself. GOATED characters.
You may have an easier time if you get Hero's Level 70 or higher. The higher it is the "slightly" better your monster's stats will be. But, do note even at level 99, you can still struggle with this rank if you don't get lucky with the RNG. Winning this Rank, really is about getting lucky, even when you got the best team.
Had to rewatch this video to see which one it was (haven't played this in a while). So at 17:33, Red is wearing the Mandarin Dress (give 133 mini medals to Princess Minnie). Hero's level is the only one that matters (as he's the top of the party formation) for the Monster Arena - He is level 73.
You can get it when you beat the dragovian master transformed into a dragon at the dragovian valley in 4 or 5 times in which he gives you super usefull items and prices, he gives you the draconid armour, you just have to equip all of the parts like jessicas bunnie fits, and then he´´ll change his apereance, this boss also gives you the best monster, improve the recipies shit and the best sword of the game, for going to this valley you must defeat the final boss, then in the postcredits you will see a statue in a high level area of the map shining, you go there and you´ll get teleported, after that you will find the origins of the hero and you will have the hardest and most epic fight in the game against this boss while he gives you loot, when you finish all, you can fight more in which you will struggle in a 7 boss combat in a row, verry epic, i beat it with my friend long ago, be carefull ot the fucking dragon azabache, he may demolish your hopes, good fortune.