Item Choices:
In the interview with Acri in Gateon Port, you can get four different items, depending on how you answer the three questions she asks you. Depending on how many of them you answer "Yes" to, the item you recieve will change. The White Herb, Mental Herb, and Quick Claw can all be purchased at Mount Battle, making the Amulet Coin the best choice.

Amulet Coin - Say "Yes" to every question.
White Herb - Say "Yes" to 2 questions.
Mental Herb - Say "Yes to 1 question.
Quick Claw - Say "No" to every question.

Get the Three Johto Starters:
To get the three Johto starters, you have to beat the 100 trainer Mt. Battle Challenge. When you do beat it, you get to pick ONE of the three Johto Starters. To get another you have to beat the 100 trainer Mt. Battle Challenge all over again. You have to beat it three times to get all three starters. It's worth it though, because they get the elemental hyper beams, frenzy plant, blast burn, and hydro cannon, which they can't get any other way but this.

Chikorita w/ frenzy plant - Beat 100 trainer Mt. Battle Challenge
Cyndaquil w/ blast burn - Beat 100 trainer Mt. Battle Challenge
Totodile w/ hydro cannon - Beat 100 trainer Mt. Battle Challenge