Attacks » Attacks in General
Do you have to attack if you have enough Energy cards attached to your Pokémon?
No, you always have the choice whether to attack on your turn or not.
Source: WotC Chat (2000-01-27)
Attacks » Attacks in General
Can I attack with a Pokémon if I just played it?
Yes, as long as it's your Active Pokémon (only your Active Pokémon can attack) and as long as it has the required amount of Energy for the attack.
Source: WotC Chat (1999-09-30)
Attacks » Attacks in General
When I attack, do I discard the Energy card(s) I used to power the attack?
Energy is not used up by an attack. Unless that attack specifically says to discard an Energy, it stays attached to the Pokémon.
Source: WotC Chat (1999-09-30)