Token copy of a Watchful Sentry, but Dragon Form was played on Watchful Sentry. Does the token get the 1 might or its new base 5 might?

The token gets 1 Might — it copies Watchful Sentry's printed traits, not the temporary effect Dragon Form is applying to the original.

Dragon Form sets the original's base Might to 5 "this turn" — that's a Layer 1 trait-altering effect, not a trait of the card itself. Copy effects only copy "copyable traits" (printed name, type, tags, cost, domain, rules text, Might), so the token enters with the printed 1 Might (Rule 477.1.b.1). Same as buffs or gear: temporary modifications are never inherited by copies (see FAQ #10049 / #10887).