What are all the episodes that Wendell speaks in?

Question

These are all his voice actors (in order):

Jo Ann Harris

Pamela Hayden

Nancy Cartwright

Russi Taylor

Answer 1

From IMDb, so not sure how accurate this is but it'll be fairly hard to work it out without re-watching every episode:

1. Homer's Odyssey (21 January 1990)  
2. Lisa's Substitute (25 April 1991)  
3. Kamp Krusty (24 September 1992)  
4. Treehouse of Horror V (30 October 1994)  
5. Grade School Confidential (6 April 1997)  
6. Das Bus (15 February 1998)  
7. Lard of the Dance (23 August 1998)  
8. Bye Bye Nerdie (11 March 2001)  
9. Little Girl in the Big Ten (12 May 2002)  
10. Lost Verizon (5 October 2008)  
11. Loan-a Lisa (3 October 2010)  
12. The Winter of His Content (16 March 2014)