Digimon summons?
Beelzemon: Double Impact
Omnimon: Grey Sword and Garuru Cannon
Dark Masters: All do their signature attacks(River of Power, Puppet Pummel, Giga Cannon, and Trump Sword)
Angewomon: Powers up Celestial Arrow while gathering energy from every single ally(so they take a bit of damage, and she adds that to her overall power. Only way to transfer it meaningfully).
WarGreymon(and BlackWarGreymon if another one is on the field. They can both show up very easily at once compared to others): Terra Force/Terra Destroyer
Shoutmon X7 Superior Mode: Final Fusion Blade(basically a one-hit kill. Brings his giant-ass sword down. So your Ultimate Chimera, since this Digimon is well beyond even Yggdrassil in terms of how ridiculously powerful he is. He took down what became an actual God in the Digital World. When you're over 100 Digimon combined, that's a bit understandable. Including multiple Megas too).
Myotismon: Crimson Lightning and Grisly Wing. He stays on the field long and is hard to defeat. ...Sound familiar? I can't think of how to properly incorporate Nightmare Wave. Hypnotism doesn't fit. Nightmare Claw, which temporarily paralyzes an enemy, could work though.
You could include anyone among the Digimelodies in Fusion too, sure.