In Diamond, Pearl, and Platinum Cheryl is a lady you meet outside of Eterna Forest, then helping her navigate through it. Gardenia is the grass-type Eterna City gym leader who loves exploring that same forest. In the anime, Cheryl gets her Mothim back from Team Rocket with help from Ash and Co. and ends up meeting Gardenia, who offers to help Cheryl find the Amber Castle. Before leaving she stops Team Rocket from stealing Mothim again.
— In the anime —
— In the games —
— Fan art —
My thoughts - If only we'd gotten to see more of these two. I imagine Cheryl asks Gardenia to walk with her in the forest even though Team Galatic isn't around anymore :,)