I also want to add that the process for discarding Energy with Blaine’s Charizard’s Roaring Flames attack is a little bit complicated when you have both single Fire Energy cards and double Fire Energy cards (like an Electrode).
Let me start first by recapping a few simple examples:
1. Blaine’s Charizard has 3 Fire Energy attached and uses Roaring Flames
Blaine’s Charizard would discard two of these Fire Energy to deal 60 damage (20+20+20).
2. Blaine’s Charizard has only Electrode attached
Blaine’s Charizard would discard this Electrode and deal 40 damage (20+20). Even though we discard two Fire Energt in this example, only Fire Energy not used to pay for the attack cost adds damage.
3. Blaine’s Charizard has only 2 Electrode attached
Blaine’s Charizard would discard both Electrodes and deal 80 damage (20+20+20+20).
4. Blaine’s Charizard has 1 Fire Energy and 1 Electrode attached
This is where things get tricky. Because Electrode must always be discarded, if you designate it as paying the attack cost, both it and the Fire Energy would be discarded, resulting in the attack doing 60 damage.
However, if you designate the Fire Energy as paying the attack cost, only the Electrode would be discarded, and you still end up with 60 damage.
In other words, whenever Blaine’s Charizard has both Electrode and regular Fire Energy (including cards like Rainbow Energy) attached, the player has can either opt to discard all of their Energy or they can choose to keep one Fire Energy and deal 20 damage less. Note that Ditto copying the attack with Double Colorless Energy would function the same way. However, the damage dealt will always be the same regardless of what is discarded.
It seems a bit confusing, but it’s very similar to paying retreat costs. Let’s say you want to retreat your Hitmonchan, which has a retreat cost of two. You can simply discard a Double Colorless Energy to retreat, but if you discard Fighting Energy first, you can then discard Double Colorless Energy, resulting in both Energies being discarded. How you designate the Energy in terms of the discard order determines what is discarded.