Finally got around to doing this...well, here is a list of the combination or team moves, the monster needed in the lead, and what they do. It's only a start, so if you can, go here to contribute: Monster Rancher Metropolis: Monster Rancher 4 Archive (PS2): Miscellaneous Q&A (Post New Questions Here) : For the Team! Discussion of Combination moves!
Lead Monster
Move Name
What It Does
Antlan
Brave Soul
Heals monsters. Guts information unknown.
Beaklon
TheLastArm
All three monsters attack, then the Beaklon again. Guts information unknown.
Dragon
Vanish Flare
Two side monsters are absorbed by energy pillars and combine with the Dragon, making him larger and stronger, the Dragon then attacks. Guts information unknown.
Ducken
HustleBall
Durahan
Knight's Valor
Monsters turn into energy balls, combine, and hit the boss. Guts information unknown.
Garu
Fire Wish
Heals all monsters. Drains all guts.
Gitan
Play
Causes "Maximize".
Golem
GigaLoad
Henger
Dive
Jell
Energize
Boosts guts
Joker
Slayer
Two side monsters turn into enrgy balls and combine with the Joker's scythe. Guts information unknown.
Ripper
Trinity
All three monsters attack, then the Ripper once more. Drains all guts.
Suezo
Iris Beam
Causes "Maximize".
Tiger
Lightning Kill
All three monsters attack, then the Tiger again. Guts information unknown.
Zuum
Last Hero
All three monsters attack, then the Zuum once more. Drains all guts.
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