Step 1: Recall the Test wicket records of each player.
- Anil Kumble (India): 619 Test wickets, one of the highest wicket-takers in Test cricket history.
- Glenn McGrath (Australia): 563 Test wickets, considered one of the greatest fast bowlers.
- Courtney Walsh (West Indies): 519 Test wickets, first fast bowler to cross 500 wickets.
- Shaun Pollock (South Africa): 421 Test wickets, known for his accuracy and all-round ability.
- Wasim Akram (Pakistan): 414 Test wickets, legendary left-arm pacer.
Step 2: Arrange in descending order of wickets.
Comparing the numbers:
Kumble (619) > McGrath (563) > Walsh (519) > Pollock (421) > Akram (414).
Step 3: Match with the given codes.
i (Kumble), iii (McGrath), ii (Walsh), iv (Pollock), v (Akram).
So the correct order is: i, iii, ii, iv, v.
\[
\boxed{\text{The correct descending order is: i, iii, ii, iv, v}}
\]