When you're battling, I'm sure you'll come to a point where you won't have a super-effective attack to use. What do you do in these situations?
You use a STAB!! STAB is the Same-Type Attack Bonus, meaning a Charizard's Flying and Fire-Type moves are boosted by 50%! This is great for these emergencies. But this isn't enough. You need an attack that is:
1) Same type as user
2) 95 Base Power or higher
3) Fairly accurate (at least 80%)
This will create a devestating blow. Also, take into account further boosts to power, ie the Magnet boosts power of Electric-Type Moves by 20%! This and STAB would give you a 70% Boost, almost doubling the attacks power. You can also strategize with abilities like Solar Power, etc to get it even higher!