If I am to understand this concept correctly, any game that has the ability to switch characters by pressing a button (as in not going to a menu) should be on this list.

The important question is do annualized sport games count? I know that you could easily switch defensive characters in ESPN NFL 2K5. This would seem to go against the spirit of the concept (The lost Vikings, Trine, etc.)

I imagine they don't count, as they're more like units than individual characters. Then again, I don't play sports games, so what the hell do I know?

They are players not characters (I don't actually know if this means anything).

I would argue that they do count, if only because some of these games have features to do the exact opposite: player-lock. The recent Maddens have all had Superstar mode, which if I recall correctly, locks your control to just that player. The most recent NBA Jam, while it isn't annualized, also has an option to enable player-lock, which brings it back in line with previous games in the series.

i was also thinking nba jam, although i was thinking the original

"Castlevania: Portrait of ruin" has a good example of what i think of when i think of this concept.

I say yes, because if that's not the name for it then where the hell do you put that style?

I think it depends on what is actually happening, if you're just switching characters that are already on the field/loaded in then that's different from when you hit a button and it loads in a different character to replace either the player or a teammate.

Usually when the term 'On-the-fly' is applied to concepts like this it relates to the latter as it's specifically stating that they have the technology to do this, which was the case with on-the-fly weapon switching in Devil May Cry 3 which if I remember correctly took a lot of effort to get working.