Stats: Fix typos in IDs

[larry-the-table-guy]

Looks like posiongem was inherited from https://github.com/smogon/usage-stats/blob/09e4b930d73acf2def123f4b2f0bffb5156bb763/TA.py#L222. From that same source, focussash appears twice but removing that would require reformatting several lines.

[scheibo]

Thanks! The snowwarning fix LGTM because that seems like a regression I introduced, but the posiongem fix should be guarded by the legacy flag (and documented in https://github.com/pkmn/stats/blob/main/stats/CHANGES.md) to remain bug-for-bug compatible with upstream.

EDIT: noticed smogon/usage-stats#15 - if that lands then this can be merged as is

[larry-the-table-guy]

Now I found several typos inherited in the aliases table. I'm thinking of adding a test case here to assert that every ID in the table actually corresponds to a Pokemon in the Dex, and then fix those here and upstream.

[larry-the-table-guy]

upstream aliases PR: smogon/usage-stats#16.

Also fixed an instance of arentrap here (not present in upstream). I'll have to check later whether it's ok to use the TRAPPING constants there or if it'll need a legacy flag.

[larry-the-table-guy]

Original code also excludes pursuit, so gated it.

[scheibo]

Thanks for the great work!