How to read a type chart without memorizing it
Type effectiveness is the single highest-leverage piece of knowledge in the game: the difference between a doubled hit and a halved one is a factor of four, which no stat advantage survives. The chart here shows all eighteen attacking types against all eighteen defending types. Pick the attacking type of the move you are planning, and each defender tile answers: green (2× — super effective), red (½× — resisted) or gray (0× — immunity, the attack does nothing at all).
Real defenders usually have two types, and the two multipliers multiply each other. Water against a Fire/Rock target is 2× times 2× = 4× — devastating. Grass against the same target is ½× times ½× = ¼× — hopeless. Immunities always win: a Normal attack against any Ghost-containing target is zero, full stop. This stacking is why the calculator on the home page asks for both defender types, and why the effectiveness line under the damage range is the first thing to check when a number surprises you.
Three habits that replace memorization
First, learn the defensive trios of the types you use most: for each of your team members, know the two or three attacking types they fear. Second, when planning an attack, check the chart for both defender types before committing — the majority of rookie mistakes are attacking a second type that resists the move. Third, remember that immunities are switches: Ground attacks hitting nothing means the opponent is switching a Flying type in, and your best move just became a wasted turn. The team guide turns these habits into a concrete team-building checklist.