English translation (please let me know if there are any errors):
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先輩たらバッチ来いです!
If you're the senpai, come in here!
さあ!
Come on!
(ぐっ)
(spread)
成長したなぴかり!
You've grown up, Pikari!
お前らバカだろう・・・
I think you're both crazy...
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いくぞ!
Let's go!
合体!
Combine!
あああっ
Aaaah!
(ジュポッ)
(SLURCH)
気持ちいいぞう! どうだ怪人!
It feels so good! How about that, mystery woman?!
(パンッ スパンッ パンッ)
(WAP FWAP WAP)
(ああッ ああッ)
(Aaah! Aaah!)
---
お・・・ おう・・・
Oh... Uhh...
エッロ
PERVERTS!
ああん テンパイもっと!
もっと激ちらパコンパコンちて!
Ooh! More, tenpai!
Do the sex stuff harder!
あまりの快感にぴかりのIQが超下がった!
Pikari's IQ suddenly dropped severly from so much pleasure!
(ハァッ ハァッ)
(Haah! Haah!)
(タプッ タプッ クチョッ)
(PLAP PLAP SQUISH)