Is Jetpack Death Seltzer legal in Standard, Modern, and Commander?

Jetpack Death Seltzer is legal in: Commander.

What type of card is Jetpack Death Seltzer?

Jetpack Death Seltzer is a Stickers. Its oracle text reads: "{TK}{TK} — Trample {TK}{TK}{TK} — {3}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.) {TK}{TK}{TK} — 2/7 {TK}{TK}{TK}{TK} — 6/5"