In the Arcade, TCG, and DS game, there are 3 different Signs (called Icons in the TCG). They are the standard Rock, Paper, and Scissors, and work exactly as the classic game always does. Their purpose and functionality between the different media varies, though the arcade and DS games almost completely share their mechanics.
A closed fist in a red block. Rock beats Scissors, but loses to Paper. When you win with this sign in the arcade, your dinosaur steps forward before swinging around and knocking your opponent over with their tail (default attack). This attack is the base Move "Tail" in the DS Game.
An open hand in a blue block. Paper beats Rock, but loses to Scissors. When you win with this sign in the arcade, your dinosaur flips your opponent up into the air and over backwards, and they land a distance away (default attack). This attack is the base Move "Throw" in the DS Game.
A hand holding up two split fingers in a yellow block. Scissors beats Paper, but loses to Rock. When you win with this sign in the arcade, your dinosaur rushes forward, ramming into your opponent and sending them skidding a distance away before collapsing (default attack). This attack is the base Move "Ram" in the DS Game.
This sign (seemingly 必 (hitsu), the Japanese kanji meaning "must" or "inevitably") corresponds only to six Super Moves from the arcade game, 1 from each Element. These Moves are stronger than most others, can only be used under certain conditions, usually occurring at random moments in a match, and require the player to properly press several series of move buttons indicated onscreen to fully execute. They are Crimson Flame, Gaia Mountain, Inazuma Phalanx (Final Thunder), Dino Force, Air Raid Storm, and Neptune Stream. Those Move Cards with the Critical sign default to count as the Move for the Dinosaur's individual Critical Move sign. This sign has no appearance outside of the arcade game.
Gameplay is broken into a series of turns, during each of which both players choose a Sign to attack with. If you choose the stronger sign, you win the turn against the opposing dinosaur and attack them, lowering their life gauge. However, your own life gauge will lower if they choose the stronger sign or if there is a tie, in which both players' life gauges are lowered by a small amount. This continues until one player's life gauge is empty. In most Story Mode battles, Reese will instruct the player through hints on which Sign to use to win that round.
All dinosaurs have an Attack stat for each of the three Signs (not the Strength stat, which dictates health; Attack is only visible on certain card versions). Two of them are typically equal, and the third one is the highest—this corresponds to the Sign of the dinosaur, and is called that dinosaur's "Critical Move". Various effects revolve around a dinosaur's Critical Move as distinguished from its other attacking signs.
Move Card signs correspond to which ones can be used together. During an arcade battle, your dinosaur can only have access to a maximum of 3 Moves, and each one has to have a different Rock-Paper-Scissors sign regardless of how many are used. Move Cards are swiped in the machine after swiping the Dinosaur Card. Some Moves only trigger when winning with their Sign, but others are instead based on winning/losing/tying regardless of Sign.
A Secret Dinosaur's three unique Moves, although they don't have separate cards, also have Signs; they are unlocked by swiping a Normal Move Card of the same Sign that specifies a recommended Technique. Also for Secret Dinosaurs, their signs' default attacks can sometimes vary due to their unique body designs or features.
The DS Game features Signs almost the exact same way as the arcade, though there are a few differences. In particular, each of a dinosaur's Signs has a different MP (Move Points) bar that is depleted when its Move is used (but regenerates over time), which can block a dinosaur from using that Sign if the Move takes more MP than is available.
All TCG Dinosaurs have Signs (called "Icons" in TCG terminology). When one attacks another, their Signs are compared. Whichever one is losing has the chance to use a Move Card first (they don't have to, but this is their only chance), then the one that won can use a Move Card (they don't have to, but this is their only chance). The advantage to winning at Rock-Paper-Scissors is that you know whether or not you need to use a Move (if there's no way you can win, you don't have to waste a card trying), or can trick your opponent into wasting a Move on a throwaway battle. In a tie, the attacker uses one first.
Very few TCG Moves have Signs, and no Normal Moves do. Those Move Cards that do have Signs (only Super Moves) can only be used by a Dinosaur of the same Element and Sign. They are either stronger than Moves with no Signs, or they are just as strong but with abilities to boot.
Notably, the strongest and Special (anime main character) Dinosaurs and Moves of a given Element tend to share the same Sign: Chomp/Lightning and Ace/Wind are Rock, Terry/Fire and Tank/Earth are Paper, and Paris/Grass and Spiny/Water are Scissors. However, Gigas is Rock and Maximus is Scissors, breaking with their Elements but aligning with the Sign references of their users. Chomp, Paris, and Tank's TCG Signs also differ from their arcade Signs for no obvious reason.
The Rock-Paper-Scissors framework has no appearance or effect in the anime, except that the Center Stone and the triangular Velociraptor Multiple Move card created by Seth feature the arcade's three-dot triangular arrangement of the Signs on them. In-series, the significance of this symbol is never addressed, and its appearances are plagued with animation errors of putting colors in the wrong order (the arrows thereby implying that Paper beats Scissors, etc.) and vary between drawn and CG renderings.
- Real life logic is used to ruin the fun by considering these conditions:
- Whenever an ankylosaurid (Earth Dinosaurs) uses the Rock default move, it would almost certainly break the bones of the opponent with its club tail. If it's a stegosaur, then the opponent's face should be jabbed to death by the thagomizer.
- All dinosaurs are not physically fit to use the Paper default move. The weight of each dinosaur shows that it is clearly not possible to throw an opponent midair. This is most evident with the sauropods (Water Dinosaurs).
- Whenever an opponent faces a ceratopsian (Lightning Dinosaurs) and uses the Scissors default move (even worse if a ceratopsian attack them with Scissors), it would be dangerous to charge in straight into them (like the animation depicts) since the sharp horns of some ceratopsians may stab into the opponent's head, perhaps killing it. Even if this charge was successful, there would be a slim chance that this action would be successful since the charging dinosaur will have to face the impact and have the energy to counter the ceratopsian's defense and push it back.
- Whenever a Secret Dinosaur uses a Sign's basic attack, the animation is often different than usual, adding to how special they are.