No no, the question (at least was phrased as) the leader is set to WereGarurumon but in order to get the target stat bonus, don't they need to be the personality of the target stat.
Which the answer is yes. (that all make sense I hope, I just answered the question the way I thought it was phrased)
Any Digimon that isn't the leader will get whatever the leaders stat type is AND whatever their own is (ie a DEF leader and Fighter Digimon that isn't the leader, the Fighter will get both Atk and DEF bonus stats).
You can of course manipulate it, change their personality via item or decrease their stat you don't want via item and just keep training them and decreasing the stat you don't want until they max out on the stat you do want.
That should work, at least it did for me in the JP version iirc.
If they are susceptible to BUG (PlatSukamon's Character Reversal) and you have a Digimon that is usually weak against them, you can infect them with BUG and use the Digimon that are usually weak against them since the strengths/weaknesses are reversed.
It's quite a genius move whenever you fight someone who can be bugged out. (not Reppamon sadly though
I tried lol)