If the 1st anticodon base is G it can pair with C as usual, in wobble rule, with U. For example, tRNA for histidine, with GUG as anticodon, can recognise both CAC and CAU codons. Similarly, if the 1st anticodon base is U, it can pair with A or G.

The last 2 bases of tRNA anticodon, which pair with first two bases of mRNA codon, pair strictly according to normal rules. But, 1st base of tRNA anticodon (which pairs with 3rd base of mRNA codon) can wobble around a little because it is not squeezed between other bases as in helix structure.

Remember that standard base pairing rules apply to bases that form part of DNA double helix. Since the codon and anticodon don't form standard double helix, slightly different rules for base pairing apply.