Attack Animal: The kitty you got from the first game becomes this in the second game. The puppy in Ice Cream becomes this somewhat, though it mans a turret instead of directly attacking.
Attack Its Weak Point: Defeating the first boss of Puppy requires you to throw the cat through the opening in its force field. Obtuse Angler from Fishy can only be hit on its bulb. Drillbaby, from the same game, needs to be defeated by dropping bombs from the ceiling onto its core.
Bag of Spilling: This is a Metroidvania series we're talking about, after all.
Bullet Hell: The fourth game, Ice Cream, can be like this, especially in Madcap mode.
Excuse Plot: Parodied in the second game, where the game opens describing an epic yet completely unrelated plot, ending with, "Meanwhile, in a completely different galaxy, thousands of light years away, Robot wants puppy." (After a wide gap between paragraphs, the story backpedals to clarify a detail in the initial plot description.)
Final Boss: Averted in every game except the last.
Fun with Acronyms: Every item in the Robot Wants JIG banner game (Crawly Bombs, Air Jump, Shield, Underminer, Actuator, Laser Blaster; Glidewings, Air Bombs, Mag-Lock, EMP Bombs, Plasma Bombs, Lateral Magnets, Aqualung, YOU WIN!note "Y? Because Robot wants it.").
Get Back Here Boss: The Battle Bat from Fishy becomes this after he loses his armor and moves faster.
Joke Item: The Sekrit Item of Wonder from Puppy is hard to find, hard to collect, and it does ABSOLUTELY NOTHING. Except unlock an award. So, yeah. In Fishy, there is an item that can only be obtained after a big chain explosion, and it is literally nothing. A nothing that you can collect. "Sometimes an explosion is its own reward."
King Mook: The iPhone version of Robot Wants Kitty has boss monsters based on the three enemies of the game.
Sequential Boss: Arguably parodied; some bosses will grow new lifebars when you so much as put a dent in their armour, with their forms showing their armour gradually being destroyed. Notably, the Final Boss of Ice Cream has five forms.
Shout-Out: There are several, especially in the boss names, such as the robotic spider "Char-L07", or the "PAL-1000", a boss whose mainframes you need to hack with the HaXXoR skill to expose the central core, which looks like HAL's red sensor.
One item in Fishy is called "Dolemite Infusion" and makes your bombs more powerful. "Dolemite" was a tough metal featured in Futurama as one component of Bender's robot body.