ONLY M.U.G.E.N

Tiny Rabbit "Fluffy" by MAITAKE

A 13-year-old bombs expert, she likes tea. There's no one inside?

YES, EVIDENTIALLY, she is based off Tiny Tina from Borderlands 2 and references several things surrounding her.

Her intro and super where she detonates explosives with a plunger reference Tina's introduction.

Her invitation to Tea Party move references her questline.

Her profile mentions she owns a gun called "Teacup" which is reference to the first weapon you get from Tina, "Teapot" and looks similar.

Typical vehicle from the series

Her win animation likely references Tina's idle animation where she would periodically flop on her bed in a stiff way.

I hardly post here now but check out this thing I converted for mugen