Fix Sky drop bugs

Most of the change is to fix

```
Start of turn 2
The foe's Aerodactyl used Sky Drop!
The foe's Aerodactyl used Sky Drop!
But Groudon is too heavy to be lifted...
```

Found the solution to the bug by checking Groudon's weight via debug, returned 9500, looked at Heavy Slam (useless) and then Grass Knot (useful).