Cook sausages on grill preheated to medium-high, 10 to 12 min. Turn occasionally, until lightly charred. Also, grill jalapeno, poblano and red peppers, 5 to 7 min., turning occasionally, until lightly charred and tender. Remove sausages and peppers from grill; thinly slice. Discard stems and seeds from peppers.
Lay half the tortilla chips in a 13 x 9-in. (3-L) foil pan. Scatter half the sausages, peppers, cheese and corn overtop. Drizzle with half the barbecue sauce. Layer on remaining chips and toppings (except green onions).
Place foil pan back on grill. Close lid. Grill 8 to 10 min., or until cheese melts. Remove from barbecue. Garnish with green onions. Serve with sour cream and lime wedges, if desired.
Alternatively, bake nachos in foil pan in 220°C (425°F) oven until cheese melts.