Darkseid has kidnapped the likes of Genki Sakura, Holly, Holly's Father, Tama and Nina from the Monster Rancher Universe, and he has also abducted the Digi-Destined children along with the Digimon Tamers children from the Digimon Universe. He means to make them all either his slaves, his brainwashed minions or his target practice dummies. In any case, he has brought them to Apokolips and has them in containment units where he means to keep them until he decides who he does what with. But he's got one big problem...the Monster Rancher goody monsters and the Digi-Good have found out of what happened, and have agreed to team up to take down Darkseid and rescue their human friends.
So, after finding a way to teleport themselves to Apokolips, specifically to Darkseid's chambers and throne room, where, sure enough, they see both Darkseid's containment units holding their human friends/partners and Darkseid himself, they all make it clear to him they will not stand for this and are either going to stop him or die trying. So Darkseid rises from his throne and informs them they have just signed their own death warrants. Now, note well that Darkseid is properly written and not being lowballed or jobbed for this fight, and that he's post-crisis, but pre-NU52 Darkseid. Also note well that he is FACING ALL OF HIS HEROIC MONSTER OPPONENTS AT THE SAME TIME, as any of them would fall to him promptly one-on-one. In addition, I would like you to note equally well that ALL the Digimon members of the Darkseid-opposing team have taken precautions and Digi-Volved to their most powerful forms. Okay, so here are Darkseid's adversaries.
From the Monster Rancher Universe, we have Tiger, Gray Wolf, Datonare, Daton, Pixie, Big Blue, Golem, Jagd Hound, Suezo, Mocchi, Hopper, Hare, Naga and Gali(all at their most powerful, and this is them post-Season 3 of the Monster Rancher Anime). And from the Digimon Adventure and Tamers Universe, we have Sakuyamon, Wargrowlmon, Beelzemon, MegaGargomon, WereGarurumon, MetalGreymon, Halsemon, Ankylomon, Magnamon, Nefertimon and Pegasusmon. Since these are their top powerful forms I'm using(or at least close to that, I might or might not be missing something), I think you can tell who possesses which ultra powerful form if you know Digimon Adventure and Digimon Tamers.
So, will the combined efforts of these heroic monsters from two different universes be enough to bring down the major league tyrant monster who is Uxas AKA Darkseid and see to the rescuing of their human friends? Or will Darkseid have more kills to boast about to his lackeys and/or enemies?