Board Thread:General Discussion/@comment-9154802-20160720182151/@comment-5718774-20160720230248

Piccolo stated that Krillin and Tien (he also said this about Gohan) were weaker than Android 20 during the early Androids Saga. We don't know how strong the Humans got, only that Krillin never surpasses Android 20 and that Tien was weaker than Android 20 but his Tri Beam was so strong it could overwhelm Semi-Perfect Cell (Tien likely got much stronger after training for seven years).