Rulings
Q1: What does this card's (Rule) mean, exactly?
This is a special rule for this card that always treats it as if it also has the Aquatic type trait.
Q2: When I use this card's End of Your Turn effect to return this card to the bottom of the deck, can I activate this card's <Decode (Blue Lv.5)> and then return 1 of my opponent's level 6 or lower Digimon to the bottom of the deck?
Yes, you can activate <Decode (Blue Lv.5)> and return a Digimon to the bottom of the deck.
Q3: I use this card's End of Your Turn effect to return this card itself to the bottom of the deck, I use this card's <Decode (Blue Lv.5)> to play a card with an On Play effect, then I attempt to return my opponent's EX6-054 Lucemon: Chaos Mode to the bottom of the deck, and EX6-054 Lucemon: Chaos Mode's All Turns effect plays a card with an On Play effect. At such times, do the On Play effects on cards played by these effects trigger simultaneously?
Yes, they trigger simultaneously.
Q4: If I activate this card's End of Your Turn effect, return this card itself to the bottom of the deck, and use this card's <Decode (Blue Lv.5)> to play BT19-025 MetalGreymon, at what timing is the DigiXros performed?
You perform the DigiXros at the timing when the card is played. You perform the DigiXros when this card's <Decode (Blue Lv.5)> is used to play BT19-025 MetalGreymon, then you choose an opponent's Digimon to return to the bottom of the deck for this card's End of Your Turn effect.
Data Sources
Lv.6 Ryugumon BT19-027 SR Mega | Data | Mollusk/LIBERATOR <Decode (Blue Lv.5)> (When this Digimon would leave the battle area other than in battle, you may play 1 level 5 blue Digimon card from its digivolution cards without paying the cost.) [When Digivolving] You may play 1 level 4 or lower blue Digimon card from this Digimon's digivolution cards without paying the cost. [End of Your Turn] [Once Per Turn] By returning 1 of your Digimon to the bottom of the deck, return 1 of your opponent's Digimon with as high or lower a level as it to the bottom of the deck. (Rule) Trait: Has [Aquatic] Type.
Lv.6 Ryugumon BT19-027 SR Mega | Data | Mollusk/LIBERATOR <Decode (Blue Lv.5)> (When this Digimon would leave the battle area other than in battle, you may play 1 level 5 blue Digimon card from its digivolution cards without paying the cost.) [When Digivolving] You may play 1 level 4 or lower blue Digimon card from this Digimon's digivolution cards without paying the cost. [End of Your Turn] [Once Per Turn] By returning 1 of your Digimon to the bottom of the deck, return 1 of your opponent's Digimon with as high or lower a level as it to the bottom of the deck. (Rule) Trait: Has [Aquatic] Type.
Lv.6 Ryugumon BT19-027 SR
Mega | Data | Mollusk/LIBERATOR
{{Decode|Blue|5}}.
[When Digivolving] You may play 1 level 4 or lower {{Colour|blue}} Digimon card from this Digimon's digivolution cards without paying the cost.
[End of Your Turn] [Once Per Turn] By returning 1 of your Digimon to the bottom of the deck, return 1 of your opponent's Digimon with as high or lower a level as it to the bottom of the deck.Lv.6 リュウグウモン BT19-027 SR 究極体 | データ種 | 軟体型/リベレイター ≪デコード《青Lv.5》≫（このデジモンがバトル以外でバトルエリアを離れるとき、このデジモンの進化元から、青のLv.5のデジモンカード1枚をコストを支払わずに登場できる） 【進化時】このデジモンの進化元から、青のLv.4以下のデジモンカード1枚をコストを支払わずに登場できる。 【自分のターン終了時】[ターンに1回]自分のデジモン1体をデッキの下に戻すことで、戻したデジモンのLv.以下の相手のデジモン1体をデッキの下に戻す。 〈ルール〉特徴:タイプ「水棲型」を持つ。