The first thing I’ll tell you is, Gallade is a good Pokémon, but level 46 is way too low to fight Red’s Pokémons, who are around level 80.
Anyway, here’s a nice move set you can use against Red.
NOTE :- The moveset that I’m going to give you is exclusively against Red, as the moves will have low PPs and are adapted only against his Pokémons.
Level :- anything but around 80
Held item :- Expert Belt
Close Combat - Red has 2 Pokémon against which fighting moves are super-effective, Lapras and Snorlax . With Gallade’s high attack, you’ll take both of them easily, but be careful of Snorlax’s Shadow ball and Crunch, which might cause harm to Gallade.
Psycho Cut - Psycho Cut will help you take out Venusaur, and hopefully you’ll land a critical hit :)
Stone Edge - With Stone Edge and Charizard’s great vulnerability to Rock-type moves, you’ll be able to take him out at one hit, if it hits.
Earthquake/Swords Dance - Earthquake will take out Pikachu easily, since light ball only improves his attack and Special attack, but not defense or Special Defense.
On the other hand, you might want to use Swords Dance on the turn Red sends Pikachu, so you can sweep the 4 other Pokémons he will send (Lapras, Snorlax, Venusaur and Charizard).
All the best to you!