Let's see if I can help any. First, we have the Imprisoning Mirrors. Most of the meta consists of Light and Dark monsters, so these can be useful. Since you're playing Cyber Dragons, however, Light-Imprisoning Mirror would hurt you, as well. As such, you're going to want other options.
One of the best options is Ghost Reaper & Winter Cherries (Pep was nowhere close to getting the name right). If you look at the effect, you can see why. You're going to want to go with the Light boss monsters as your targets, such as Dante, Cyber Dragon Infinity, and ABC-Dragon Buster (currently OCG). Another good target is Toadally Awesome (Treatoad; currently OCG), since that's going to be another prominent card in the meta. If you're worried about your Blue-Eyes match-up, you can also go with Blue-Eyes Spirit Dragon.
Ghost Ogre & Snow Rabbit is another good side deck card, as it destroys a card that activates its effect. Be aware that it doesn't negate, unless the card needs to remain face-up on the field to resolve.
Imperial Iron was is a great option against both Kozmos and ABCs. Against Kozmos, the opponent can't use the effects that require them to banish for their effects (basically every card in the deck). Against ABCs, they can't summon Dragon Buster. If Dragon Buster is already on the field, they can't use the effect of it. (While we're on the topic of ABCs, don't use Non-Fusion Area. Dragon Buster's summon doesn't count as a Fusion Summon.)
Kaijus are good options for removing monsters that you have trouble getting rid of. Most people prefer Gameciel, since it has the lowest ATK of all of them. I don't really like it because it's Level 8, so if it has to stay on the field against Blue-Eyes (for whatever reason), they can use it for an Xyz. I prefer Kumongous since it only has 200 more ATK and it's Level 7. In your case, however, I would go with Jizukiru. Even though it has the most ATK, it's a Machine, so you can easily remove it with Chimeratech Fortress Dragon.
Mask of Restrict is another good option. Some people will still play Monarchs, so it can be used against those. It can also be used again Cyber Angel Herald (which isn't meta, but it's a somewhat common rouge deck). They're another Light deck, so this is a good option for them since you can't really use Light-Imprisoning Mirror. Majespecters aren't played too often, but they're another thing that can be stopped with Mask of Restrict. Since their spells and traps require them to tribute a monster, this would prevent them from doing so.
The last one off the top of my head is Anti-Spell Fragrance. It can be used against any Pendulum deck (prevents them from setting their scales), Blue-Eyes (which play a lot of spells), and Cyber Angel Herald (making them have to wait a turn to Ritual Summon their monsters).
I hope this was helpful. Good luck on your side deck.