You all know how it goes, most of the time, the higher the risk, the higher the reward. But in some cases, the higher the consequence.
You'll see all about this in my section regarding this!
Hyper Beam, and Giga Impact
Thses are what some may consider, power house moves. They have amazing power, but, they can be the reason why you lose a battle.
They both have a little(BIG) aftermath, you have to rest a turn, to recharge. In that one turn, that Pokemon, can be beaten.
Think carefully when using these moves.
Rest
Ah, the classic Snorlax move. Rest, can be the saving grace for your Pokemon, or it can be it's demise.
It can heal your Pokemon fully, but it puts it in a depp slumber. It can wake up soon, and start retaliating against the attacking
Pokemon. Or, it can stay there, and be constantly assaulted, and perhaps K.O.ed, by the attacking Pokemon.
You might want to have a berry attached, that will wake it up, as soon as it falls asleep.
Sunny Day, Rain Dance
Usually, these moves aren't a problem, but, they can be used against you easily. Say you have a Venusaur, and you a facing a Charizard, you use Sunny day, so you can use SolarBeam instantly (Not a smart idea, against Charizard), Charizard's fire moves get an extra power boost, and that Fire Blast he may use next, may be the last Fire Blast your Venusaur will see this battle.
Rain Dance can be a problem too. I added this move, because I flashed back to my Emerald playing days. Wallace used Rain Dance, with his Wailord, and my Slaking just happened to know Thunder. Need I say more?
Conclusion
Make sure you think before you act. The ultimate pwer, can be the ultimate downfall....