G2IV

JM53, MK73, and Houk88 do not list a G2IV standard.

Keenan89 lists four G2IV standards: HD 126868, HD 196755, HD 206301
(42 Cap), and HD 217014. Also a G2IV-V Fe-1 standard is given (HD
31966).

GrayNstars lists phi Vir (HR 5409, HD 126868) and kap Del (HR 7896, HD
196755) as their G2IV standards.

# Standards
HD 126868 = HR 5409 = Phi Vir (J1428-0213, V=4.8)
  G2IV: Keenan80,Keenan89,Gray01,GrayNStars
  G2III: Jaschek64(most)
  G2IIIb: Abt81
  G2III+G4V: Edwards76 
  G3V: Houk99
  G0:III:: Bouw81
  F9IV: Eggen52
  K0: Cannon
  5" pair. Revised HIP data leads to Mv=2.01, 3.05 mag above MS
  B-V=0.693. In Hertzsprung gap. F9-K0 in the literature, but
  most recent literature agrees on "G2". 

# Weak Standards
HD 206301 = HR 8283 = HIP 107095 = 42 Cap 
  G2IV: Keenan89,Jaschek78(Roman52(lines strong)),Jaschek64(all)
  G2V: Gray89
  G1IV: Gray06
  G5: Cannon
  B-V=0.672, revised HIP => Mv=2.55, 2.38 mag above MS. 

HD 196755 = HR 7896 = kap Del 
  G2IV: Keenan89,Harlan74
  G5IV: Jaschek64(most),Roman55,Roman52
  G5: Cannon
  G3V: Abt85
  G0IV-V: Lutz77
  B-V=0.702. revised HIP => Mv=2.68, 2.4 mag above MS. 
  Star has oscillated between G0 and G5. 

HD 217014 = HR 8729 = 51 Peg
  G2V: Gray01
  G2IV: Keenan89
  G5V: Cowley79,Jaschek78(Harlan70)
  G3V: Gray03
  G4V: Stebbins57
  G0: Cannon
  Famous planet host, whose evolutionary status I recalled discussed
  in an IAU circular after the planet was found in 1995. 
  B-V=0.666. Revised HIP data => Mv=4.48, so 0.41 mag above MS.
  Temperature types are in G0-G5 range. Clearly a dwarf, only considered
  subgiant by Keenan89. Do not recommend as a standard.