Hide 'n' Seek Battle Monster Tactics

Hide 'n' Seek Battle Monster Tactics, in Japan called Kakurenbo Battle Monster Tactics (かくれんぼバトルモンスタータクティクス, lit. Hide and Seek Battle Monster Tactics), sometimes simply called Monster Tactics (モンスタータクティクス) is a hybrid strategy/RPG game published by Nintendo for the Game Boy Color on November 21, 2000.

Tropes used in Hide 'n' Seek Battle Monster Tactics include:

Betting Minigame (slot machines in a casino on B4 that will let you win Jewels sometimes)
Can't Drop the Hero
Critical Hit (Taren's natural skill is capable of having increased attack)
Cute Bruiser (Kaen)
Early Bird Boss (Kratora, not even the Target Monster of B1, has high HP to go with his Fire element that can easily threaten Kevin--which makes it hilarious that the floor's Target Monster, Wyneck, is weaker and is only accompanied by an easily killed Marlinger)
Elemental Rock-Paper-Scissors
Everything's Better with Penguins (Presma, the second target monster of B5)
Everything's Better with Princesses (Sylphy is the princess of a distant country, and even comes with a butler)
Exposition Fairy (Toppy)
Fake King (it explains King Klein's evil look)
Fiery Redhead (Kaen)
Five-Man Band (Kevin as the Hero, Kaen as the Lancer, Taren as the Smart Guy, Sylphy as the Chick, and Goum as the Big Guy)
Fog of War (the premise of this game)
Game Breaker (Taren and Sylvia)
Glass Cannon (Goum, but subverted a bit in that damage attacks on his front are reduced even further by the direction multiplier, and he has so many HPs to work with)
Gotta Catch Em All (the Montacs, which you get for defeating the different types of monsters, along with the individual monster types' moves)
He Knows About Timed Hits (Although some players may have trouble learning how to play through the game anyway, every time you start over you have to deal with Toppy telling you.)
Heroic Mime (Kevin)
Hit and Run Tactics (and how)
The Mentor (Gunter who joins if you clear the secret doors of B6)
Mighty Glacier (Goum, as a somewhat subverted Glass Cannon)
Puzzle Boss (Hemataitos, one of the B7 Target Monsters, whom you defeat by using Bombs)
The Rival (Ryan but he joins when Klein gets in the way of the tournament)
That One Boss (Trinchula, B5's first Target Monster, quite possibly even if you use Kaen)
Useless Useful Spell (averted to the point of making Taren a Game Breaker thanks to a learnable paralysis technique that's along the way; and on your side, Gunter is immune to status effects)
Warmup Boss (Nightmare, the first monster you fight in Fog of War)
We Cannot Go on Without You (And we cannot let the enemy kill their own leader, either.)