Popple

Popple is a thief from the Beanbean Kingdom in Mario & Luigi: Superstar Saga. He has had two partners, Bowser (known as the time as Rookie), and Birdo. Popple finally returns in Mario & Luigi: Dream Team.

Enter: The Shadow Thief
Popple is first seen right after Mario and Luigi exit the Barrel Maze in the Chateau de Chucklehuck. Mario notices a strange person behing him instead of Luigi. The person runs off and the Mario Bros. chase after him. They meet up with the person and another, larger guy who looks familiar. The person introduces himself as Popple: The Shadow Thief and his partner Rookie. Mario and Luigi already could tell Rookie is actually Bowser but he has lost his memory at some point (right after he got launched out of the cannon at Stardust Fields). The four get into a battle with the Mario Bros. eventually becoming victorious. Popple and Rookie escape going after the precious Chuckola Cola. The duo return right after Mario and Luigi opened up the way past Chuckleroot going after the Cola. Unlucky for them, Popple and Rookie are soon seen tied up and got knocked away by Bubbles' living Chuckola Cola monster.

The Return of the Shadow Thief
Popple and Rookie return after Mario and Luigi defeated Cackletta and the Beanstar went down to the basement of Woohoo University. They are happy with their greatest find until they see the Mario Bros. at the front door. Popple is unhappy but is confindent on winning thanks to his own versions of the Bros. moves with Rookie. They were once again unsuccessful in defeating the Mario Bros. but they weren't going down without a fight. After the Beanstar goes mad, they all latch onto it with everyone falling off (Bowser regains his memory after crashing through the ceiling but falls right into Stardust Fields badly injured and is eventually turned into Bowletta).

The Shadow Thief Goes Solo
Popple is seen again at Chucklehuck Woods, this time,  trying to reach a piece of Beanstar near the Winkle Arena and eventually gets it. However, he spots Mario and Luigi and tries to escape but gets boxed in by the duo. Without Rookie at his side, Popple is forced to fight by himself to keep his Beanstar piece. He loses badly and runs off promising to get back at the Mario Bros.

The Shadow Thief Strikes Back
Popple returns for the final time underground of Teehee Valley noticing a knocked-out Luigi. He then orders his new "Rookie" to tie him up knowing Mario isn't far. After the Mario Bros. are reunited, Popple shows up again saying victory his defintally within his reach as he introduces his new Rookie: Birdo. However, Birdo has a crush on him with constantly freaks him out. They all eventually get into a fight with Popple coming on the losing end once again. He is extreamly angry at Birdo for causing his loss and even fires her. Birdo is greatly upset and knocks away Popple.

Aftermath
Popple is seen in Little Fungitown where he is finally arrested for his crimes and is seen doing communtity service. Ironically, the Toad guard watching over him calls him "Rookie."

The Shadow Thief in the Pi'illo Kingdom
Popple is first seen at Wakeport after bumping into Mario and Luigi. He talks about how much he hated people that looked that Mario and Luigi and has started fresh in the Pi'illo Kingdom to steal treasure and runs off. Popple is seen again at Driftwood Shore where he is seen in a small tour group. Popple is disappointed that he can't get much further knowing there is rare treasure beyond that point so he decides to leave. Poople is seen again at Mount Pajamaja where he was running away from an area. He said that there was loose footing and he isn't the climbing type and decides to back to Wakeport. Popple is seen again at Wakeport near the same house from eariler where he claims that he has finally found some treasure. He then leaves claiming he has found the map. Popple is seen again shortly saying he has found the way to the hidden treasure. However, he spots a Wiggler walking about enjoying the view. Popple is angry and believes that the Pi'illo Collector has hired a security guard and decides to act cautious. Mario and Luigi soon start getting closer to the Wiggler but Popple quickly stops them but thinks they're also thieves. Mario and Luigi deny this but Popple still thinks so as he keeps running into them over his quest. Popple then thinks to himself saying he will use Mario and Luigi to defeat the Wiggler while he steals the treasure. Popple then wants to team up with them to take down the "fuzzball". Popple then leads time to the Wiggler but accidently starts a fight between them. During the fight, even though Popple aids Mario and Luigi, his antics actually cause Mario and Luigi to almost lose their focus during the fight. However, after Mario and Luigi defeat the Wiggler, Popple decides to fight Mario and Luigi himself. Popple is soon defeated by Mario and Luigi and he realizes that the Wiggler isn't a guard and yells about the flower garden. Angry, the Wiggler chases off Popple with the Shadow Theif saying he is done with Pi'illo Island.