Best way to use 2 Arduinos

I have a Mega with using a 3.3 volt AREF on a sensor input and using a 200ms delay in the loop to slow down the sensor reading on serial display. I would like to add another sensor at value at 5 volts to the same display with minimal delay.
Since the delay is in the loop I think I would have to
use another Arduino for my 200ms delayed sensor,
output that delayed signal to an input on my Mega (master)
and output that to the serial display having the less delayed sensor(s) strait to Mega (master) to display on another portion of the serial screen.
Is that correct, or is there a more accurate easier way to do this?

Yes, invest in a pencil. Think through your ideas on paper.

e.g. loop every 100ms. Read the first sensor every second loop. Read the second sensor every fifth loop.

The Arduino has already got a timer e.g. millis()

I will let you draw your flow diagram when you have bought the pencil.
Show your flow. Ask if you do not undestand.

Good Luck.