Cheapest priced copy (Commander Legends): $0.35 at Card Kingdom, near mint, their price list as of .
Squad Captain 
Creature — Human Soldier · 2/2 · Common · Foundations Jumpstart · #257
Vigilance (Attacking doesn't cause this creature to tap.)
This creature enters with a +1/+1 counter on it for each other creature you control.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Legends | 51 | Common | $0.35 | $0.49 |
| Foundations Jumpstart | 257 | Common | $0.35 | — |
| Core Set 2020 | 38 | Common | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 12 July 2019If Squad Captain somehow enters the battlefield at the same time as another creature you control, it doesn't count that other creature. It counts only creatures that are already on the battlefield.