Shaggy is the most powerful being
Thanos: Punches at full force with all six infinity stones

Shaggy: Catches fist effortlessly "Like nice try dude, you almost made me use 10% of my power"

Thanos: Activating power stone "YOU HAVEN'T SEEN ANYTHING YET"

Shaggy: pushing Thanos to the side easily with a bored expression on his face

Thanos: teleporting behind Shaggy "Nothin-"

Shaggy: suddenly behind Thanos "-g personal kid " slamming Thanos into the ground

Thanos: trys to snap

Shaggy: puts scooby snack in Thanos's hand

Thanos: breaks scooby snack getting dust everywhere

Scooby snack: "Like man, I dont feel so good"

Thanos: uses times stone to go back to a previous position whilst healing himself

Shaggy: "Like, man just give up"

Thanos: "The world will die without balance!" activates power stone and punches ground causing earthquake

Shaggy: puts single finger to the ground stopping the vibrations immediately "I guess you want to do this the hard way"

Shaggy: rushes towards Thanos the sheer speed creating small wisps of flames. Before suddenly stopping right in front of Thanos about to punch him

Thanos: quickly grabs Shaggys arm and attempts to throw him

Shaggy: firmly planting his feet into the ground

Thanos: Now just trying to throw him to the side

Shaggy: heavily damaging the ground as Thanos trys to throw him

Shaggy: effortlessly tosses Thanos into the ground behind Shaggy breaking every bone in Thanos's arm

Thanos: Screams in extreme pain right before trying to reverse time again

Thanos: realizes that time stone is gone

Shaggy: "Looking for this" tries to spin stone on finger but just clumsily drops it

Thanos: tries to crawl to stone while it's on the ground

Shaggy: picks up stone "Well anyways" picks up Thanos by the neck "We're done here"

Thanos: looks directly at camera "Well it looks like we're in the Avengers: Endgame coming April 26th 2019 now"