First take a look at Defender's text:
Then take a look at one of the questions bangiras translated from the Japanese FAQ:
Q: When a Drifblim with a “Defender” attached to it uses its “Balloon Tackle” attack, is Drifblim’s self-damage reduced by 20 due to the effect of Defender?
A: Yes, it’s reduced by 20.
I think you see where I'm going with this. The English scan says the damage reduction from Defender only applies for an opponent's attack, but the FAQ contradicts that.
I think PUI needs to either:
A: Stop doing a half arse job translating cards
B: Hire bangiras

Then take a look at one of the questions bangiras translated from the Japanese FAQ:
Q: When a Drifblim with a “Defender” attached to it uses its “Balloon Tackle” attack, is Drifblim’s self-damage reduced by 20 due to the effect of Defender?
A: Yes, it’s reduced by 20.
I think you see where I'm going with this. The English scan says the damage reduction from Defender only applies for an opponent's attack, but the FAQ contradicts that.
I think PUI needs to either:
A: Stop doing a half arse job translating cards
B: Hire bangiras