In the Ghosts 'n Goblins playthroughs, when Arino first meets the Red Arremer he runs away, losing a life but skipping the demon by reaching a checkpoint. It's very satisfying to see him getting over his fear and carefully taking down the Arremers when forced to fight them in the end-game.
Despite having some trouble with stages 2 and 4, Arinoppa the Rapper beat Parappa The Rapper in just about 4 hours.
Any time Arino finishes a game on a 24-hour or less live events.
His victory on his third attempt at Pilotwings was truly miraculous. On his last try and with little time left, he had finally finished off all the enemy turrets on the last level. Under immense pressure, he still had to land the helicopter successfully, which he does, right as the game started complaining he was descending too fast!
Arino finishing Ninja Spirit in a mere 2 hours.
The AD's have their own Crowning Moments of Awesome, including...
Inoko MAX, having spent most of the fifth season screwing up in one way or another, redeems himself in the finale by getting the good ending of "Shadow Land". Much later, in Season 16, he gets another when Arino bets on him in Barcode Battle and he wins.
From Tokimeki Memorial, Arino successfully romances Shiori on his first try, a feat considered near impossible.