Anything that can boost it's evasion/somehow stop the opponent from attacking will give the opponent a hard time hitting it. Following are two examples (one is legal, the other though...):
Togekiss @ Leftovers
Ability: Serene Grace
EVs: 4 HP / 252 SpA / 252 Spe (varies as per the set's bulkiness)
- Thunder Wave/Body Slam
- Air Slash
This thing was one of the most rage inducing Pokemon ever, because it utilized what they call, "ParaFlinch". In this strategy, the opponent is first Paralyzed rendering them unable to attack 25% of the time and considerably slowing them down. Then it is followed by a flinching move, in this case Air Slash which get's a 60% flinch chance from Serene Grace.
Here's the probability of it getting hit after it's set up:
Original chance of move hitting = 100%
Chance of move after paralysis = 100 - 25% of 100 = 75%
Chance of move hitting through flinch = 75 - 60% of 75 = 30% chance
And yeah. That was the legal example.
Froslass @ Bright Powder
Ability: Snow Cloak
EVs: 252 HP / 4 Def / 252 Spe
- Thunder Wave
- Confuse Ray
NOTE: This is not legal in smogon format since it has Snow Cloak.
People are gonna hate me for even mentioning this one e.e
Here's how disaster begins: First, Froslass comes under Hail, so it gets an evasion boost from Snow Cloak. Then, it continues to Paralyze, Confuse and Attract you. It probably won't happen though. But after that, well, you've got no choice but to wait out the Hail and/or switch out, because there's no way you're thinking straight if you're trying to attack. Here's the odds:
Original chance of hitting = 100%
Chance of hitting after through Snow Cloak = 20% of 100 = 80%
Chance of hitting through confusion = 50% of 80 = 40%
Chance of hitting through paralysis = 40 - 25% of 40 = 30%
Chance of hitting through infatuation = 50% of 30 = 15% chance
Hope I helped!