Mecha Neena is a boss in HTFA 6, appearing in the second level of Bowser's Fortress. She's Neena's evil knockoff.
Her boss room in that game features a flat ground with two floating platforms (one on each side) to stand on and make jumping over her easier. Mecha Neena attacks by causing a small tidal wave and firing missiles from her feet. Note that this boss will always follow the player, so he/she has to move away if she gets too near.
Gallery
Mecha Neena in HTFA 6.