Rulings
Q1: Does this card's effect also prevent me from using Option card effects to play Digimon?
Yes. Option card effects are effects just like any other, so you can't use them to play Digimon.
Q2: If this Digimon is in play, can I activate effects that reduce play costs?
Yes. Effects that only reduce play costs can still be activated. Effects that reduce play costs AND play Digimon can’t be activated.
Data Sources
EN
Official English Card Listworld.digimoncard.com
Lv.3 Pillomon BT9-033 C Rookie | Vaccine | Mammal [All Turns] Players can't play Digimon by effects.
A
Official English (Asia) Card Listen.digimoncard.com
Lv.3 Pillomon BT9-033 C Rookie | Vaccine | Mammal [All Turns] Players can't play Digimon by effects.
W
DCG Wikidigimoncardgame.fandom.com
Lv.3 Pillomon BT9-033 C rookie | Vaccine | Mammal [All Turns] Players can't play Digimon by effects.
JP
Official Japanese Card Listdigimoncard.com
Lv.3 ピロモン BT9-033 C 成長期 | ワクチン種 | 哺乳類型 【お互いのターン】お互いは効果でデジモンを登場できない。