A note on DLC fighters: Remember what fighters were DLC in Smash 4, not counting veterans.
- Ryu
- Cloud
- Corrin
- Bayonetta
Those are some heavy-hitters (well, except for Corrin, but he's an outlier). And given that we've already got some "blockbuster" characters added to the launch roster (Daisy, Ridley, Simon, K. Rool), I can't see DLC being a step
down from that, especially since they have to be purchased separately. They have to be characters people will shell out extra money for, not ones that will get a lukewarm reception from most audiences.
So I find it hard to believe that they'll sell a Pokémon as DLC. They can get away with adding Lucario and Greninja to the roster despite their limited appeal because they're in the regular game with all the other characters, not being sold separately. I don't see Incineroar or Lycanroc being DLC when people are still waiting on contenders from the ballot.
Big names and third parties are more likely for DLC than anything else. Especially since the licensing deals can be handled individually, after all the other licensing deals for the main game and its third parties have been handled.