Following info comes from Car 15.
Here's Roach, Elgar and Rygog.
Here's Roach.
Here's Elgar and Roach.
Here's Rockin' Roach.      
Here's a shot of the Rangers and Rockin' Roach fighting even though all 5 Rangers are fighting this bug.
Here's the Giant Rockin' Roach. Rockin' Roach wasn't shown eating the food that would have enlarged him.
Here's a shot of Giant Roach using a Paint Brush in order to paint a heart on a building.
Here's a shot of Roach and Robo Racer fighting.
Here's a shot of Roach going in to attack the Turbo Megazord and Robo Racer however the Turbo Megazord and the Robo Racer use their Shields in order to try to block the Roach's attack.
Rockin' Roch wasn't destroyed, he just reverted back into his small bug form and Lady Z took him back with her.