Pokemon: Raticate [Normal type]
Move: Facade [Normal type]
Item: Flame Orb
Ability: Guts
Facade is a move that has a power of 70, and when the Pokemon gets poisioned, paralyzed, or burned, this move's power doubles. And the ability Guts boosts the Pokemon's attack when it has a status problem. The Flame Orb burns the holder, so if you give it to a Raticate, you can inflict double the damage. And since Raticate and the move Facade have the same type, the attack's power is boosted even more.

Type: Electric or Steel
Move: Magnet Rise [Electric type]
Ground type moves are a common type weakness for Electric and Steel type Pokemon, but if you use Magnet Rise, you can nullify Ground type moves for 5 turns. This is an exeptionally good combo for Electric types, since their only weakness is Ground type moves. So wnen this move is used, the user technically has no weaknesses. This combo is best used by a fast Pokemon, so they can use this move first.

Move 1: Endure [Normal type]
Move 2: Reversal [Fighting type] or Flail [Normal type]
The move Endure makes your Pokemon endure any attack the opponent throws at you, leaving 1 HP, and the move Reversal or Flail increases in power when the Pokemon's HP is lower. So when you use Reversal or Flail with only 1 HP left, you can inflict lots of damage! It's also a good idea to have your Pokemon hold the Focus Sash, an item that allows the holder to endure a potential one-hit KO attack, instead of using the move Endure.

Pokemon: Rampardos [Rock type]
Item: Focus Sash
Rampardos is a Pokemon with a very, very, high Attack, but low Defense, and an even lower Sp. Defense. Have this Pokemon hold the Focus Sash so you can endure the opponent's super-effective Earthquake attack, then make them pay by inflicting lots of damage on them.