Can you play Monster Hunter online on the Nintendo Switch version?
I want to buy this game here soon and why is there "Generations" and "Ultimate" on 1 cart on it?
Yes you can.
The game is called, there are not more on it.
Should work online, since MonsterHunter has always been a game with a great co-op mode.
However, you need a paid online subscription to play with other people over the Internet. If you play with friends in the same room, the free, local online mode can be used.
The game is called "Generations Ultimate", but it only contains one game.
However MonsterHunter "Generations" has already been released for the Nintendo 3DS. With the switch version you get a fancy "Generations" version, which has been extended by many quests. "Ultimate" is thus probably a more challenging version of MH Generations.
If you have gambled on the 3DS already, you have the option to transfer your score to the Switch.