Coding help

I have been working on trying to get a new ability for a Pokemon I created to work, but nothing I do seems to work, so I'm coming here to see if maybe someone can help me.

It should be a simple ability, but when trying to copy similar abilities that already exist it won't work.

I just want an ability where if the Pokemon gets hit by a physical attack he changes from. I don't want it to be like disguise, where there is no or limited damage. Just a simple, got with a physical attack -- change form.

I technically have two Pokemon with similar abilities, but one changes when hit by a special attack. I figure if I can get the one to work I should be able to get the other one to work.

Anyway, and help would be appreciated