I wasn't really talking about side decks, but more like side products. For YGO, for me at least, would be any booster set released in the OCG and it's TCG counterpart that is part of the 8 color booster rainbow pattern, as well as the 2 structure decks and the one starter deck that is released both in the OCG and TCG. Everything else would be a side product, whether it be the TCG exclusive starter of structure decks, (You can argue that it is a main product if you don't count the OCG), battle packs, legendary collection, dragons of legend type booster packs, tins, etc.
For Pokemon TCG, a main product is the 4 booster sets that they release every year. Examples would be XY, XY Flashfire, Black and White Legendary Treasures, Plasma Blast etc. The 2 theme decks that come with the set are also main products. It is hard to figure out whether kalos starter set is a main or a side product, considering how Legendary Treasures never had theme decks, and how these are supposed to be the replacement.
There are side products in the Pokemon TCG, but they are either not legal in tournaments, like the world champ decks, or they contain any combination of the main products packaged into one box + one or more single promo cards. What I would like to see are actual side products, whether they be precons or booster packs, and not something where they bundle different main products in a box + one single promo. I am not saying that they should discontinue box sets, I am just saying that they should do less of them, and in place, make completely brand new precons or a specialized booster set, whether they be a set built for draft, or a very small all-holo set, like they did with dragon vault.
So all in all, less box sets, more products like these. I basically made up my own schedule as to what TPCi should release as an annual basis. This is one of those things.
Main booster sets and their associated theme decks are released in February, May, August, and November.
In March and September, they normally release the tins.
In April and October, they should release the battle arena vs decks.
In December, they should release the all holo precon deck like the red genesect collection.
In June, they should release a set of 3 precons costing $25 that contains an EX card as a cover card, typically, each one contains an EX card from one of each of the any of the main sets released the previous year, so if something like this released this June, it would contain one EX card from either Plasma Storm, Plasma Freeze, Plasma Blast, or Legendary Treasures, most likely those that haven't been released in Tins before, or maybe just release a set of brand new exclusive to this precon EX cards. Another thing about these decks, is that unlike theme decks, they contain pokemon cards from multiple sets. Theme decks contain cards that are only from their set, with the exception of trainers, which can be from any set so long as they are in the same series. These are different. As long as at time of release, the card is standard legal, it is fair game. As I said before, these would be in the same packaging as the Kalos Starter set deluxe decks, which means they contain one random booster from the last few latest sets, and due to the nature of the packaging, being able to see 3 cards and all, the featured cards should all be black star promo alternate art EX card, Rare holo pokemon, and a holo trainer card.