After defeating Marnie & Hop in the Semi-Finals and defeating all three Gym Leaders that stand before you in the Finals, you will finally proceed to facing Leon in order to become the next Galar Region Champion. Leon is the strongest trainer in the entire Galar Region, and much like his younger brother, he will use a variety of different Pokemon.
No matter what Starter Pokemon you chose, Leon will always have Aegislash, Dragapult, Haxorus and Charizard as four of the six members apart of his Pokemon Team. Because of this, it would be wise to have a Dark Type (for both Aegislash & Dragapult), an Ice Type (for Haxorus & Dragapult), and a Rock Type (for Charizard) within your Party. Leon's fifth Pokemon (Seismitoad, Mr. Rime, Rhyperior) will always be weak against your Starter Pokemon, while his last Pokemon, the Starter Pokemon he kept at the start of the game, will always be effective against yours. Because of all of this, if five of your six Pokemon are a Dark Type, Ice Type, Rock Type, your Starter Pokemon, and a Pokemon that's effective against Leon's Starter Pokemon, you should be in good shape when facing him.
Additionally, all of Leon's Pokemon will either be at Level 62, Level 63, level 64 or Level 65. Due to this, it would be wise to have all of your Pokemon at Level 70 or higher. The more experienced your Pokemon are, the easier it will be to defeat Leon. And finally, Leon will Gigantamax his final Pokemon, which just so happens will be Charizard. Because of this, it would be especially wise to wait to use your Dynamax until he sends out his Charizard. Also, it would be smart if the Pokemon you Dynamax is either an Electric Type, Water Type or Rock Type, since Leon's Charizard will still be extremely weak against those types of Pokemon.
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