I could honestly say that the Tamagotchi Connection V5 / Tamagotchi Familitchi has probably one, if not, the hardest set of games ever placed inside the Tamagotchi. 

TV Surfing is one tough game to master and complete successfully despite it being the first of two games available for the V5.  It gets annoyingly difficult around the 7-9 mark that more often than not, you get it wrong because your reaction time was too slow.  Tea Time is a slightly easier variation of the Flag game found in the V4.  The challenge there is distinguishing the cup standing upright from the cup lying on their side as they have little variation between each other.  There is also the "game trick" where none of the cups can be filled with tea because they are both lying on the side.  Golf Putt is another timing game that can be likened to the TV job in the V4.  It's more achievable than the TV Surfing game, but you have to concentrate a lot as the arrow can get really fast, and you need to putt 30 times.

Then there is the Shoe Pairs game.  Albeit only available starting fron generation 2 onwards, Shoe Pairs, the game where your eldest child plays with the mother and match shoes together, is probably the easiest and most fruitful game in the Tamagotchi V5.  You only need 20 matches, speed is challenging but bearable (not as fast as golf putt and TV Surfing) and you have a 4-5 pixel leeway for the shoes.  It also adds 30 bonding points (note: points, not percentage) if you successfully complete everything.