Most type-based damage decisions come down to four ideas: STAB, weakness, resistance, and immunity. Once those are clear, the type chart becomes a decision tool rather than something you need to memorize all at once.
STAB rewards attacks that match the user
Same-Type Attack Bonus applies when a Pokémon uses a damaging move that matches one of its types. In standard situations the multiplier is usually 1.5×, although abilities and newer battle mechanics can modify the result.
That makes STAB moves the reliable core of many offensive sets. Coverage moves are added to solve targets that the main STAB attacks cannot handle well.
A weakness increases incoming damage
If the defending Pokémon is weak to the move's type, the attack is super effective and normally deals 2× type-effectiveness damage. A dual-type Pokémon can be weak through both types, producing a 4× multiplier.
This is why looking only at the first listed type can be misleading. Both defensive types participate in the matchup.
A resistance reduces incoming damage
A resistance normally reduces type-effectiveness damage to 0.5×. If both defensive types resist the same attacking type, the multiplier can become 0.25×.
Resistances are important for switching because they can turn an otherwise strong attack into an opportunity for a teammate to enter safely.
An immunity can cancel the attack entirely
Some type relationships deal no damage under ordinary conditions. Ground attacks do not normally affect Flying-type Pokémon, for example. Abilities, items, field effects, and special move rules can create exceptions, so always consider the complete battle state.
Immunities are especially valuable because they can create a free switch when the opponent is locked into or strongly expected to use the blocked attack.
Dual types multiply the two relationships
For a dual-type defender, calculate the move against both types and multiply the results. A move that is super effective against one type but resisted by the other usually becomes neutral overall. Two weaknesses combine to 4×; two resistances combine to 0.25×.
This multiplication is the fastest way to understand unusual matchup results without memorizing every dual-type combination.
Coverage is about important targets, not collecting colors
A coverage move is valuable when it helps a Pokémon beat something that otherwise stops it. A move can be super effective against many types and still be a poor choice if those targets are not relevant to the team.
Start with your STAB options, identify the Pokémon that resist or wall them, and then choose coverage that addresses those specific answers.
Use the type chart as a planning tool
Before a battle, use Dex Atlas's type chart to inspect repeated weaknesses across your team. During team building, check whether you have safe responses to the attacking types your core Pokémon invite.
The goal is not to eliminate every weakness. It is to make sure weaknesses are covered by teammates, speed, priority, offensive pressure, or another reliable plan.