One of the most powerful of these long-lasting staples that could find a home even in the decks of today would be the regular side-deck and tech card Skill Drain, whose powerful effect can negate all face-up monster effects on the field for the cost of just 1000 life points
Then, if this Digimon has 12000 DP or more, it gains Security Attack +1 for the turn
Then, not even a year later, two top meta decks come out that annihilate the competitive landscape and have easy access to an extremely strong level seven Digimon without even needing to get a level six on the field
BT5-112 SEC Digimon Lv.7 Alternative Art Omnimon Zwart Defeat Color White Cost 15 DP 13000 Digivolve Cost 1 BlackPurple 3 from Lv.6 Form Mega Attribute Virus Type Holy Warrior Card Text 1 [Effect] [Security] Play this card without battling and without paying the cost
2 Scar-Red Dragon Archfiend Scar-Red Dragon Archfiend is a card that offers a solid level of protection while also being one of the most offence-driven cards in the Deck
Here are some other name combinations to try, as I found here: SD01