Guess you won’t realize it, but Cure Tender as an enemy reminds me of Brainwashed Aira Harune due for being butterfly themed. Also, they has the red eye which is almost alike while Aira has a butterfly in her eyes. As an extra, I’ll give another two pics for both mouth (Tender) and eye (Aira) in their evil mode respectively. While we’ll wait how much long Maria will remained as an enemy until being purified by Innocent Purification (most probably 2 episodes), Aira will probably done the longest as she’s being manipulated by the Mysterious Symphonia Dress Stone in the end of Episode 35 (thinking just Symphonia, quitting Pretty Top with MARs’ other members and joining Symphonia Selection, which she is glad of like Kintaro Asechi) and until Episode 42 thanks to PURETTY’s efforts. (spoiler if you didn’t watch Dear My Future whole yet) Who knows if Cure Tender’s dark appearance will be replayed again in the pre-opening like Aira in Episode 38 later.
For the below Episode Source, the brainwashed butterfly-themed enemy appears in the end of the same numbered episode. The coord Aira wears along with Rhythm’s “Pure White Wedding Coord (ピュアホワイトウェディングコーデ Pyua Howaito U~edingu Kōde)” and Mion’s “Romantic Night Wedding Coord” (ロマンティックナイトウエディングコーデ Romantikku Naito Uedingu Kōde) in Pure Stone, is “Mysterious Symphonia Dress” (しんぴのシンフォニアドレス Shin pino Shinfonia Doresu), “Dreaming Symphonia Pumps” (ゆめみるシンフォニアパンプス Yumemiru Shinfonia Panpusu) and “Papillon Sunglasses” (パピヨン サングラス Papiyon Sangurasu)
Happiness Charge Pretty Cure Episode: 37, “The Brokened Big Bang! Truly Unexpected Vigor Foe Appears!” (やぶられたビッグバーン！まさかの強敵登場！ Yaburareta Biggu Bān! Masaka no Kyōteki Tōjō!)
Pretty Rhythm Dear My Future Episode: 37, “"Aira’s Decision” (あいらの決断 Aira no Ketsudan)