How did he bowl ? Straight up the middle ? try to put a small hook ? That would make a difference in what I'd suggest.
If he's pretty much a straight bowler, go with a plastic ball, T Zone, W/D. If you has or wants to put a small hook to it, I'd say a Tornado maybe a Power Groove but not much more than that. Have him learn target, hit the target first. Doesn't have to be the pocket but a mark, a board. Once he has that down then go for a break point then the pocket, slow steps. If you rush someone they can get frustrated and then it's not fun and they may well loose interest.
JMO
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az guy aka: R & L Bowlers Pro
rlbowlerspro@cox.net