Frankie is one of the main antagonists of the show.
While Sandy was trying to convince Blinky to become a television star, Frankie was out looking for a house to rob. He climbed up a tree, just outside of Sandy's bedroom window, and saw her talking to both Blinky and Pinky. After seeing the talking koalas he decided to tell Spike about it immediately, as he was sure someone pay a lot of money to see them.
When Spike heard about the talking bears he had Frankie return to Sandy's home and climb up to the window to steal them. He saw Blinky just sitting in the window and thought he was in luck, but upon returning to Spike's hideout he realizes that he isn't as lucky as he thought. Blinky was asleep, so Spike assumed he was just a stuffed animal and nothing more. Since he thought Nlinky was worthless he took his watch and then tossed him out a window.
Frankie thought he'd never seen Blinky again, but managed to come across him out in the city streets. He informs Spike that he found the talking koala and the two of them run off to try and capture him.